arm64: mm: Add additional parameter to uaccess_ttbr0_enable

Add an extra temporary register parameter to uaccess_ttbr0_enable which
is about to be required for arm64 PAN support.

This patch doesn't introduce any functional change but ensures that the
kernel compiles once the KVM/ARM tree is merged with the arm64 tree by
ensuring a trivially mergable conflict with commit
27a921e757
("arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN").

Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

arch/arm64/mm/cache.S

@@ -49,7 +49,7 @@ ENTRY(flush_icache_range)
  *	- end     - virtual end address of region
  */
 ENTRY(__flush_cache_user_range)
-	uaccess_ttbr0_enable x2, x3
+	uaccess_ttbr0_enable x2, x3, x4
 	dcache_line_size x2, x3
 	sub	x3, x2, #1
 	bic	x4, x0, x3
@@ -80,7 +80,7 @@ ENDPROC(__flush_cache_user_range)
  *	- end     - virtual end address of region
  */
 ENTRY(invalidate_icache_range)
-	uaccess_ttbr0_enable x2, x3
+	uaccess_ttbr0_enable x2, x3, x4
 
 	invalidate_icache_by_line x0, x1, x2, x3, 2f
 	mov	x0, xzr