xen/arm: use BSD sed compatible regexp in SRCARCH

Convert the ARM SRCARCH variable setting to use the more common 'arm.*'
expression rather 'arm\(32\|64\)', as the later doesn't work with BSD sed
for not being a basic regular expression.  The usage of | alternations is
not part of basic regexp support.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

xen/Makefile

@@ -242,7 +242,7 @@ include $(XEN_ROOT)/Config.mk
 
 ARCH := $(XEN_TARGET_ARCH)
 SRCARCH := $(shell echo $(ARCH) | \
-    sed -e 's/x86.*/x86/' -e 's/arm\(32\|64\)/arm/g' \
+    sed -e 's/x86.*/x86/' -e 's/arm.*/arm/g' \
         -e 's/riscv.*/riscv/g' -e 's/ppc.*/ppc/g')
 export ARCH SRCARCH