To make the matrix initialization code sharing with other SoCs,
move it from SAMA5D4 particular file,
mach-at91/armv7/sama5d4_devices.c to a separate file,
mach-at91/matrix.c

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Reviewed-by: Andreas Bießmann <andreas.devel@googlemail.com>