mb/[google/intel/lenovo]/*: fix posix shell bug with SPD files

FreeBSD's sh (basic posix shell) did not interpret the '\%o' escape
in the same way bash/zsh do. As a result, the decoded files ended up
with ASCII numbers instead of the decoded binary data.

Change-Id: I95b414d959e5cd4479fcf100adcf390562032c68
Signed-off-by: Greg V <greg@unrelenting.technology>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35867
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/mainboard/intel/kunimitsu/spd/Makefile.inc

@@ -43,7 +43,7 @@ SPD_DEPS := $(foreach f, $(SPD_SOURCES), src/mainboard/$(MAINBOARDDIR)/spd/$(f).
 $(SPD_BIN): $(SPD_DEPS)
 	for f in $+; \
 	  do for c in $$(cat $$f | grep -v ^#); \
-	    do printf $$(printf '\%o' 0x$$c); \
+	    do printf $$(printf '\\%o' 0x$$c); \
 	  done; \
 	done > $@