powerpc:Fix return type & parameter passed for I/O functions

Return type of in_8, in_be16 and in_le16 should not be'int'. Update it to type
u8/u16/u32.
Although 'unsigned' for in_be32 and in_le32 is correct. But to make return type
uniform across the file changed to u32

Similarly, parameter passed to out_8, out_be16, out_le16 ,out_be32 & out_le32
should not be 'int'.Change it to type u8/u16/u32.

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>