Revert "mwifiex: cancel pcie/sdio work in remove/shutdown handler"

This reverts commit b713bbf1.

The "fix" in question does not actually fix all related problems, and it
also introduces new deadlock possibilities. Since commit b014e96d
("PCI: Protect pci_error_handlers->reset_notify() usage with
device_lock()"), the race in question is actually resolved (PCIe reset
cannot happen at the same time as remove()). Instead, this "fix" just
introduces a deadlock where mwifiex_pcie_card_reset_work() is waiting on
device_lock, which is held by PCIe device remove(), which is waiting
on...mwifiex_pcie_card_reset_work().

The proper thing to do is just to fix the deadlock. Patch for this will
come separately.

Cc: Signed-off-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>