kernel/generic: modify mtd related patches for 3.14

Function register_mtd_parser always returned 0 (at least since v3.3)
before being changed to return void in v3.14-rc1~65^2~93 (mtd: make
register_mtd_parser return void), so it's not needed to check the
return value of this function. Also add __init flag to caller.

This fix compile errors in 3.14 kernel like:
drivers/mtd/mtdsplit_seama.c: In function 'mtdsplit_seama_init':
drivers/mtd/mtdsplit_seama.c:99:2: error: void value not ignored as it ought to be
  return register_mtd_parser(&mtdsplit_seama_parser);
  ^
kernel: modify mtd related patches for 3.14

The change is the same as ("kernel/generic: modify mtd related
patches"). Since these files are under files directory, not a files
directory of specific kernel version, better to also change them. So
it will avoid adding files to future specific files directory
(e.g. files-3.14) for this mtd related change.
ar71xx: modify patch mtd-m25p80-allow-... for 3.14

Related upstream change: v3.14-rc1~65^2~150 ("drivers: mtd: m25p80:
convert "bool" read check into an enum").
ar71xx: modify mtd related patches for 3.14