Currently qfw_locate_file() always prints error messages when it can't
find a file. This causes unwanted error output in qemu_get_bootcmd()
when the optional "opt/u-boot/bootcmd" file doesn't exist.
Adjust qfw_locate_file() to be silent, with a new qfw_locate_file_msg()
that shows messages.
This allows callers to choose whether missing files should generate
error messages.
Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
eb2dc2bac8