EFI: further "need_to_free" adjustments

EFI: further "need_to_free" adjustments

When processing "chain" directives, the previously loaded config file
gets freed. This needs to be recorded accordingly such that no error
path would try to free the same block of memory a 2nd time.

Furthermore, neither .addr nor .size being zero has any meaning towards
the need to free an allocated chunk anymore. Drop (from read_file()) and
replace (in Arm's efi_arch_use_config_file(), to sensibly retain the
comment) respective assignments.

Fixes: 04be2c3a0678 ("efi/boot.c: add file.need_to_free")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>