mx6sabreauto: Remove unneeded SPL selection

SPL option is already selected via Kconfig, so remove it from the
CONFIG_SYS_EXTRA_OPTIONS line.
Signed-off-by: NFabio Estevam <fabio.estevam@nxp.com>

configs/mx6sabreauto_defconfig

@@ -8,7 +8,7 @@ CONFIG_SPL_MMC_SUPPORT=y
 CONFIG_SPL_SERIAL_SUPPORT=y
 CONFIG_SPL_LIBDISK_SUPPORT=y
 CONFIG_SPL_WATCHDOG_SUPPORT=y
-CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/mach-imx/spl_sd.cfg,SPL"
+CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/mach-imx/spl_sd.cfg"
 CONFIG_BOOTDELAY=3
 # CONFIG_CONSOLE_MUX is not set
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y