Setting the NVMEM stride to 4 means we can't have nvmem cells pointing
at odd addresses. Linux sets it to 1 instead and handles reads at
unaligned addresses by splitting them up to aligned chunks. Copy over
the code to do the same. Unaligned writes remain illegal.

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>