wil6210: Fix potential memory leaks on error paths

Fix missing memory deallocation on error paths in wil_write_file_wmi()
and wil_write_file_txmgmt().

Change-Id: I5b86ff2dee9deb0ce357a76e0e70d1ef6470a8fe
Reported-by: Ahmed Tamrawi <ahmedtamrawi@gmail.com>
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Git-commit: 8e09b7d2dbb86eb3e9a714d6622f4da24e988029
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-testing.git


Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>