Merge pull request #25 from yongbok/i6400-mips64r6-PRIP4

Add support for .MIPS.ABIflags in user-mode

Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>
target-mips: fix cpu_mips_validate_access()

type casting is required for 64 bit address

Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>
target-mips: update cpu definitions

P5600, MIPS32R6-generic, and I6400

Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>