UPSTREAM: ath10k: remove deprecated fw_crash_dump debugfs file

The fw_crash_dump file was deprecated by commmit 727000e6 ("ath10k: support
dev_coredump for crash dump") in v4.11 in favor of dev_coredump interface,
remove it now for good. Everyone should use dev_coredump now.

Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Git-commit: d333bdd9b0653b525494cd7f9f9d3b9350e4bbd3
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


Change-Id: Ide8573611573dcce1d47f1c2c21f6de13ef790b0
Signed-off-by: Dundi Raviteja <dundi@codeaurora.org>