ARM: 8436/1: hw_breakpoint: remove unnecessary header

Header <asm/kdebug.h> is not needed for arm/hw_breakpoint.c, so remove
the pointless #include.

Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Reviewed-by: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>