Revert "sunxi: psci: avoid error address-of-packed-member"

Using memcpy() for some MMIO access is generally frowned upon and might
break things on some platforms. Allwinner H3, which fails to boot, being
an example here.

Moreover, fields being accessed are naturally aligned and warnings
produced by GCC have been quiesced for some time already by:

53dc8ae6 ("gcc-9: silence 'address-of-packed-member' warning")

That said, it should be okay to revert this commit.

This reverts commit 9bd34a69.

Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
Acked-by: Jagan Teki <jagan@amarulasolutions.com>