aspeed/soc: Support I2C for AST2700

aspeed/soc: Support I2C for AST2700

Add I2C model for AST2700 I2C support.
The I2C controller registers base address is start at
0x14C0_F000 and its address space is 0x2000.

The AST2700 I2C controller has one source INTC per bus.
I2C buses interrupt are connected to GICINT130_INTC
from bit 0 to bit 15.
I2C bus 0 is connected to GICINT130_INTC at bit 0.
I2C bus 15 is connected to GICINT130_INTC at bit 15.

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