plat: imx8mm: provide uart base as build option

Some boards (f.e. Verdin i.MX8M Mini) use different UART base address
for serial debug output, so make this value configurable (as a
build option).
Signed-off-by: Igor Opaniuk <igor.opaniuk@gmail.com>
Change-Id: I988492ccecbc3f64a5153b381c4a97b8a0181f52

plat/imx/imx8m/imx8mm/include/platform_def.h

@@ -47,7 +47,6 @@
 
 #define HAB_RVT_BASE			U(0x00000900) /* HAB_RVT for i.MX8MM */
 
-#define IMX_BOOT_UART_BASE		U(0x30890000)
 #define IMX_BOOT_UART_CLK_IN_HZ		24000000 /* Select 24MHz oscillator */
 
 #define PLAT_CRASH_UART_BASE		IMX_BOOT_UART_BASE

plat/imx/imx8m/imx8mm/platform.mk

@@ -51,3 +51,6 @@ $(eval $(call add_define,BL32_BASE))
 
 BL32_SIZE		?=	0x2000000
 $(eval $(call add_define,BL32_SIZE))
+
+IMX_BOOT_UART_BASE	?=	0x30890000
+$(eval $(call add_define,IMX_BOOT_UART_BASE))