plat/arm: Enable MULTI_CONSOLE_API in AArch32

Set MULTI_CONSOLE_API=1 for both AArch64 and AArch32 by default.
MULTI_CONSOLE_API=0 is still supported, but it has to be set from the
command line.

Change-Id: I4eeaa8e243a3fe93ed8a716e502666a26ad28f35
Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>

plat/arm/common/arm_common.mk

@@ -126,9 +126,7 @@ SEPARATE_CODE_AND_RODATA	:=	1
 LOAD_IMAGE_V2			:=	1
 
 # Use the multi console API, which is only available for AArch64 for now
-ifeq (${ARCH}, aarch64)
-  MULTI_CONSOLE_API		:=	1
-endif
+MULTI_CONSOLE_API		:=	1
 
 # Use generic OID definition (tbbr_oid.h)
 USE_TBBR_DEFS			:=	1