efivars: If pstore_register fails, free unneeded pstore buffer

efivars: If pstore_register fails, free unneeded pstore buffer

This is patch 3/3 of a patch set that cleans up pstore_register failure paths.

If efivars fails to register with pstore, there is no point to keeping
the 4 KB buffer around. It's only used by the pstore read/write routines.

Signed-off-by: Lenny Szubowicz <lszubowi@redhat.com>
Reported-by: Naotaka Hamaguchi <n.hamaguchi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
(cherry picked from commit 0d838347f1325cebfe8b9341a4b4c1f407022231)
Signed-off-by: Mark Brown <broonie@linaro.org>