MIPS: OProfile: Add CPU_P5600 cases

Add a CPU_P5600 cpu type case in oprofile_arch_init() to use the MIPS
model, and in mipsxx_init() to set the cpu_type string to "mips/P5600".

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Robert Richter <rric@kernel.org>
Cc: oprofile-list@lists.sf.net
Patchwork: https://patchwork.linux-mips.org/patch/6410/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>