meson: place default firmware path under .../share

Fixes: c09c1ce7e9 ("configure: switch directory options to automatic parsing", 2022-05-07)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/meson-buildoptions.sh

@@ -42,7 +42,7 @@ meson_options_help() {
   printf "%s\n" '  --enable-trace-backends=CHOICES'
   printf "%s\n" '                           Set available tracing backends [log] (choices:'
   printf "%s\n" '                           dtrace/ftrace/log/nop/simple/syslog/ust)'
-  printf "%s\n" '  --firmwarepath=VALUE     search PATH for firmware files [qemu-firmware]'
+  printf "%s\n" '  --firmwarepath=VALUE     search PATH for firmware files [share/qemu-firmware]'
   printf "%s\n" '  --iasl=VALUE             Path to ACPI disassembler'
   printf "%s\n" '  --includedir=VALUE       Header file directory [include]'
   printf "%s\n" '  --interp-prefix=VALUE    where to find shared libraries etc., use %M for'