mtd: move support for struct flash_platform_data into m25p80

This "type" seems to be an extra hint for m25p80 about the flash. Some
archs register flash_platform_data with "name" set to "m25p80" and then
with a real flash name set in "type". It seems to be a trick specific
to the m25p80 so let's move it out of spi-nor.
Btw switch to the spi_nor_match_id instead of iterating spi_nor_ids.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>