efi_loader: Prevent dereferencing NULL pointer

efi_loader: Prevent dereferencing NULL pointer

Taking the first goto error: in file_open could either result in an
attempt to dereference fh when NULL or else free fh->path which has
not been assigned to and so will be unknown. Avoid both of these
problems by passing path to free instead of fh->path.

This issue found by Smatch.

Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>