spi: meson-axg: add SPICC driver support

Add new compatible string to support SPICC controller which
found at Amlogic Meson-AXG SoC. This is aiming at adding
a couple of enhanced feature patches.

Signed-off-by: Sunny Luo <sunny.luo@amlogic.com>
Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
Signed-off-by: Mark Brown <broonie@kernel.org>