pc-bios/s390-ccw: Fix the cc-option macro in the Makefile

The cc-option macro is not doing what it should - compared with the
original from the rules.mak file that got removed with commit
660f793 ("Makefile: inline the relevant parts of rules.mak"),
the arguments got changed and thus the macro is rather doubling
the QEMU_CFLAGS than adding the flag that should be tested.

Message-Id: <20210502174836.838816-3-thuth@redhat.com>
Fixes: 22fb2ab ("pc-bios/s390-ccw: do not use rules.mak")
Signed-off-by: Thomas Huth <thuth@redhat.com>

pc-bios/s390-ccw/Makefile

@@ -6,8 +6,8 @@ include ../../config-host.mak
 CFLAGS = -O2 -g
 
 quiet-command = $(if $(V),$1,$(if $(2),@printf "  %-7s %s\n" $2 $3 && $1, @$1))
-cc-option = $(if $(shell $(CC) $1 -S -o /dev/null -xc /dev/null > /dev/null \
-	      2>&1 && echo OK), $1, $2)
+cc-option = $(if $(shell $(CC) $1 $2 -S -o /dev/null -xc /dev/null \
+			 >/dev/null 2>&1 && echo OK),$2,$3)
 
 VPATH_SUFFIXES = %.c %.h %.S %.m %.mak %.sh %.rc Kconfig% %.json.in
 set-vpath = $(if $1,$(foreach PATTERN,$(VPATH_SUFFIXES),$(eval vpath $(PATTERN) $1)))