xen: fix header guard generation for asm-generic headers

Dashes were wrongly not translated into underscores, thus generating
an unexpected guard identifier.

Fixes: ee79f37831 ("xen: add header guards to generated asm generic headers")
Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

xen/scripts/Makefile.asm-generic

@@ -34,7 +34,7 @@ unwanted    := $(filter-out $(generic-y) $(generated-y),$(old-headers))
 quiet_cmd_wrap = WRAP    $@
       cmd_wrap = \
 	arch=$$(echo $@ | sed -n 's:.*arch/\([^/]*\)/.*:\1:p' | tr a-z A-Z); \
-	upper=$$(echo $*.h | tr a-z A-Z | tr '/.' '__'); \
+	upper=$$(echo $*.h | tr a-z A-Z | tr '/.-' '__'); \
 	echo "\#ifndef $${arch}_GENERIC_$${upper}" > $@.new; \
 	echo "\#define $${arch}_GENERIC_$${upper}" >> $@.new; \
 	echo "\#include <asm-generic/$*.h>" >> $@.new; \