Fixes the following W=1 kernel build warning(s):

 drivers/mtd/nand/raw/omap2.c:191: warning: Function parameter or member 'info' not described in 'omap_prefetch_enable'
 drivers/mtd/nand/raw/omap2.c:221: warning: Function parameter or member 'cs' not described in 'omap_prefetch_reset'
 drivers/mtd/nand/raw/omap2.c:221: warning: Function parameter or member 'info' not described in 'omap_prefetch_reset'
 drivers/mtd/nand/raw/omap2.c:946: warning: Function parameter or member 'chip' not described in 'omap_enable_hwecc'
 drivers/mtd/nand/raw/omap2.c:946: warning: Excess function parameter 'mtd' description in 'omap_enable_hwecc'
 drivers/mtd/nand/raw/omap2.c:1017: warning: Function parameter or member 'chip' not described in 'omap_dev_ready'
 drivers/mtd/nand/raw/omap2.c:1017: warning: Excess function parameter 'mtd' description in 'omap_dev_ready'
 drivers/mtd/nand/raw/omap2.c:1036: warning: Function parameter or member 'chip' not described in 'omap_enable_hwecc_bch'
 drivers/mtd/nand/raw/omap2.c:1036: warning: Excess function parameter 'mtd' description in 'omap_enable_hwecc_bch'
 drivers/mtd/nand/raw/omap2.c:1142: warning: Function parameter or member 'ecc_calc' not described in '_omap_calculate_ecc_bch'
 drivers/mtd/nand/raw/omap2.c:1142: warning: Excess function parameter 'ecc_code' description in '_omap_calculate_ecc_bch'
 drivers/mtd/nand/raw/omap2.c:1270: warning: Function parameter or member 'ecc_calc' not described in 'omap_calculate_ecc_bch_sw'
 drivers/mtd/nand/raw/omap2.c:1270: warning: Excess function parameter 'ecc_code' description in 'omap_calculate_ecc_bch_sw'
 drivers/mtd/nand/raw/omap2.c:1284: warning: Function parameter or member 'ecc_calc' not described in 'omap_calculate_ecc_bch_multi'
 drivers/mtd/nand/raw/omap2.c:1284: warning: Excess function parameter 'ecc_code' description in 'omap_calculate_ecc_bch_multi'
 drivers/mtd/nand/raw/omap2.c:1681: warning: Function parameter or member 'info' not described in 'is_elm_present'
 drivers/mtd/nand/raw/omap2.c:1681: warning: Function parameter or member 'elm_node' not described in 'is_elm_present'
 drivers/mtd/nand/raw/omap2.c:1681: warning: Excess function parameter 'omap_nand_info' description in 'is_elm_present'

Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Jian Zhang <jzhang@ti.com>
Cc: linux-mtd@lists.infradead.org
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Signed-off-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20201109182206.3037326-20-lee.jones@linaro.org