Add TTBR operator for kasan_init

Add TTBR operator for kasan_init

The purpose of this patch is to provide set_ttbr0/get_ttbr0
to kasan_init function. The definitions of cp15 registers
should be in arch/arm/include/asm/cp15.h rather than
arch/arm/include/asm/kvm_hyp.h, so move them.

Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Joel Stanley <joel@jms.id.au>
Tested-by: Abbott Liu <liuwenliang@huawei.com>
Signed-off-by: Abbott Liu <liuwenliang@huawei.com>