mtd: intel-dg: Fix accessing regions before setting nregions

mtd: intel-dg: Fix accessing regions before setting nregions

The regions array is counted by nregions, but it's set only after
accessing it:

[] UBSAN: array-index-out-of-bounds in drivers/mtd/devices/mtd_intel_dg.c:750:15
[] index 0 is out of range for type '<unknown> [*]'

Fix it by also fixing an undesired behavior: the loop silently ignores
ENOMEM and continues setting the other entries.

CC: Gustavo A. R. Silva <gustavoars@kernel.org>
CC: Raag Jadav <raag.jadav@intel.com>
Reported-by: Jani Partanen <jiipee@sotapeli.fi>
Closes: https://lore.kernel.org/all/caca6c67-4f1d-49f1-948f-e63b6b937b29@sotapeli.fi
Fixes: ceb5ab3cb646 ("mtd: add driver for intel graphics non-volatile memory device")
Signed-off-by: Lucas De Marchi <demarchi@kernel.org>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Reviewed-by: Raag Jadav <raag.jadav@intel.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>