aspeed/sdmc: Add AST2700 support

aspeed/sdmc: Add AST2700 support

The SDRAM memory controller(DRAMC) controls the access to external
DDR4 and DDR5 SDRAM and power up to DDR4 and DDR5 PHY.

The DRAM memory controller of AST2700 is not backward compatible
to previous chips such AST2600, AST2500 and AST2400.

Max memory is now 8GiB on the AST2700. Introduce new
aspeed_2700_sdmc and class with read/write operation and
reset handlers.

Define DRAMC necessary protected registers and
unprotected registers for AST2700 and increase
the register set to 0x1000.

Add unlocked property to change controller protected status.

Incrementing the version of vmstate to 2.

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