ARM: 6505/1: kprobes: Don't HAVE_KPROBES when CONFIG_THUMB2_KERNEL is selected

Currently, the kprobes implementation for ARM only supports the ARM
instruction set, so it only works if CONFIG_THUMB2_KERNEL is not
enabled.

Until kprobes is updated to work with Thumb-2, turning it on will
cause horrible things to happen, so this patch disables it for now.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>