mtd: spi-nor: fix erase_type array to indicate current map conf

BFPT advertises all the erase types supported by all the possible
map configurations. Mask out the erase types that are not supported
by the current map configuration.

Backward compatibility test done on sst26vf064b.

Fixes: b038e8e3

 ("mtd: spi-nor: parse SFDP Sector Map Parameter Table")
Reported-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>