powerpc: configs: Add VFAT file-system configs

Add CONFIG_NLS_CODEPAGE_437, CONFIG_NLS_CODEPAGE_850,
CONFIG_NLS_ISO8859_1 in default configs for 85xx
and 86xx socs. Required for mounting vfat file-systems
on USB devices

Signed-off-by: Ramneek Mehresh <ramneek.mehresh@freescale.com>
Signed-off-by: Nikhil Badola <nikhil.badola@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>