omapfb: fix IOCTL parameter types

IOCTL parameters shouldn't be of an enum type, replace them with int.

This also fixes up the places where u8, u16, u32 was used instead of
__u8, __u16, __u32 for things used by user space.

This solves a bug for IOCTL code mismatch between kernel and user space
because the toolchains used generated different value for sizeof(enum
xxx) and this size is encoded in the IOCTL code.

Signed-off-by: Imre Deak <imre.deak@nokia.com>
Signed-off-by: Juha Yrjölä <juha.yrjola@nokia.com>