ARM: 5866/1: arm ptrace: use unsigned types for kernel pt_regs

Make registers unsigned for kernel space. This is important for
example in the perf events where the PC is stored into a u64. We
don't want it sign extended so make the regs unsigned to prevent
casts throughout the kernel.

Signed-off-by: Jamie Iles <jamie.iles@picochip.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>