plat: imx: imx8qm: provide debug uart num as build param

This removes hardcoded iomux/clk/addr configuration for debug uart,
provides possibility (as a workaround, till that information isn't
provided via DT) to set this configuration during compile time via
IMX_DEBUG_UART build flag.

Usage:
$ make PLAT=imx8qm IMX_DEBUG_UART=1 bl31

Signed-off-by: Igor Opaniuk <igor.opaniuk@gmail.com>
Change-Id: Ib5f5dd81ba0c8ad2b2dc5647ec75629072f511c5
diff --git a/plat/imx/imx8qm/platform.mk b/plat/imx/imx8qm/platform.mk
index 5ba9c3f..20ee05b 100644
--- a/plat/imx/imx8qm/platform.mk
+++ b/plat/imx/imx8qm/platform.mk
@@ -43,3 +43,9 @@
 ERRATA_A53_835769	:=	1
 ERRATA_A53_843419	:=	1
 ERRATA_A53_855873	:=	1
+
+IMX_DEBUG_UART		?= 	0
+$(eval $(call add_define,IMX_USE_UART${IMX_DEBUG_UART}))
+
+DEBUG_CONSOLE		?= 	0
+$(eval $(call add_define,DEBUG_CONSOLE))