Get rid of confusing function (superceeded by
`grub_ieee1275_get_integer_property')
* include/grub/ieee1275/ieee1275.h (grub_ieee1275_decode_int_4): Remove
prototype.
* kern/ieee1275/ieee1275.c (grub_ieee1275_decode_int_4): Remove
function.
* term/ieee1275/ofconsole.c (grub_ofconsole_init): Avoid use of
grub_ieee1275_decode_int_4(), by obtaining integer properties directly
in native endianess from grub_ieee1275_get_integer_property().