arm: armv7: allow unaligned memory access

The UEFI spec mandates that unaligned memory access should be enabled if
supported by the CPU architecture.

This patch implements the function unaligned_access() to reset the aligned
access flag in the system control register (SCTLR). It is called when the
bootefi command is invoked.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
[agraf: fix SPDX identifier]
Signed-off-by: Alexander Graf <agraf@suse.de>