aspeed/smc: Add AST2700 support

aspeed/smc: Add AST2700 support

AST2700 fmc/spi controller's address decoding unit is 64KB
and only bits [31:16] are used for decoding. Introduce seg_to_reg
and reg_to_seg handlers for ast2700 fmc/spi controller.
In addition, adds ast2700 fmc, spi0, spi1, and spi2 class init handler.

AST2700 is a 64 bits quad core CPUs(Cortex-a35). Introduce a new
"aspeed_2700_smc_flash_ops" and set its valid "max_access_size"
8 for 64 bits data format access.

Signed-off-by: Troy Lee <troy_lee@aspeedtech.com>
Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>