soc/intel/quark: Set temporary I2C base address

Set a temporary I2C base address during romstage.

TEST=Build and run on Galileo Gen2

Change-Id: I4b427c66a4e7e6d30cc611d4d3c40bb0ea36066d
Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-on: https://review.coreboot.org/15006
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

src/soc/intel/quark/include/soc/iomap.h

@@ -25,7 +25,8 @@
 #define UART_BASE_ADDRESS		CONFIG_TTYS0_BASE
 
 /* I2C/GPIO Controller */
-#define I2C_GPIO_BASE_ADDRESS		0xa0020000
+#define I2C_BASE_ADDRESS		0xa0020000
+#define GPIO_BASE_ADDRESS		0xa0021000
 
 /*
  * I/O port address space