arm64: Fix missing #include in hw_breakpoint.c

A prior commit used to detect the hw breakpoint ABI behaviour based on
the target state missed the asm/compat.h include and the build fails
with !CONFIG_COMPAT.

Fixes: 8f48c062 ("arm64: hw_breakpoint: use target state to determine ABI behaviour")
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/hw_breakpoint.c

@@ -28,6 +28,7 @@
 #include <linux/ptrace.h>
 #include <linux/smp.h>
 
+#include <asm/compat.h>
 #include <asm/current.h>
 #include <asm/debug-monitors.h>
 #include <asm/hw_breakpoint.h>