lightnvm: pblk: consider max hw sectors supported for max_write_pgs

When do GC, the number of read/write sectors are determined
by max_write_pgs(see gc_rq preparation in pblk_gc_line_prepare_ws).

Due to max_write_pgs doesn't consider max hw sectors
supported by nvme controller(128K), which leads to GC
tries to read 64 * 4K in one command, and see below error
caused by pblk_bio_map_addr in function pblk_submit_read_gc.

[ 2923.005376] pblk: could not add page to bio
[ 2923.005377] pblk: could not allocate GC bio (18446744073709551604)
Signed-off-by: NZhoujie Wu <zjwu@marvell.com>
Reviewed-by: NJavier González <javier@cnexlabs.com>
Signed-off-by: NMatias Bjørling <mb@lightnvm.io>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

drivers/lightnvm/pblk-init.c

@@ -407,6 +407,8 @@ static int pblk_core_init(struct pblk *pblk)
 	pblk->min_write_pgs = geo->ws_opt;
 	max_write_ppas = pblk->min_write_pgs * geo->all_luns;
 	pblk->max_write_pgs = min_t(int, max_write_ppas, NVM_MAX_VLBA);
+	pblk->max_write_pgs = min_t(int, pblk->max_write_pgs,
+		queue_max_hw_sectors(dev->q) / (geo->csecs >> SECTOR_SHIFT));
 	pblk_set_sec_per_write(pblk, pblk->min_write_pgs);
 
 	pblk->pad_dist = kcalloc(pblk->min_write_pgs - 1, sizeof(atomic64_t),