ARM: armv7: Add C wrapper for allow_unaligned()

Rename current assembler implementation of allow_unaligned() to
v7_arch_cp15_allow_unaligned() and add it into armv7.h header,
then add C wrapper of allow_unaligned().

This fixes misbehavior when linking U-Boot on ARMv7a i.MX6Q, where the
CPU specific allow_unaligned() implementation was ignored and instead the
__weak allow_unaligned() implementation from lib/efi_loader/efi_setup.c
was used, which led to "data abort" just before booting Linux via tftp,
in efi_dp_from_file() -> path_to_uefi() -> utf16_put() .

The problem is triggerd by c7c0ca37673 ("efi_loader: fix efi_dp_from_file()") .
Adding the wrapper fixes the problem.

Fixes: 78f90aaeecc ("arm: armv7: allow unaligned memory access")
Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/arch/arm/cpu/armv7/cpu.c b/arch/arm/cpu/armv7/cpu.c
index 68807d2..6259ffa 100644
--- a/arch/arm/cpu/armv7/cpu.c
+++ b/arch/arm/cpu/armv7/cpu.c
@@ -83,3 +83,8 @@
 {
 	return cleanup_before_linux_select(CBL_ALL);
 }
+
+void allow_unaligned(void)
+{
+	v7_arch_cp15_allow_unaligned();
+}