ov13858: fix endiannes warnings

3 warning regressions:
  + drivers/media/i2c/ov13858.c: warning: cast to restricted __be32:  => 1093:16
  + drivers/media/i2c/ov13858.c: warning: incorrect type in assignment (different base types):  => 1111:13
  + drivers/media/i2c/ov13858.c: warning: incorrect type in initializer (different base types):  => 1071:27

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>