brcmfmac: Fix 'did not remove int handler' warning

brcmf_sdiod_intr_unregister call that removes both func1 and
func2 interrupt handlers only called when brcmf_ops_sdio_remove
is called for func 1 (which is the 2nd call) but sdio is expecting
it to be removed at the end of each sdio_remove call.
This is causing 'rmmod bcmrfmac' on a 4356-sdio chip to complain
with:
WARNING: driver brcmfmac did not remove its interrupt handler!

The modification makes calling brcmf_sdiod_intr_unregister multiple
times harmless by clearing the variables that track if interrupt
handlers have been installed, and then calls it on every
brcmf_ops_sdio_remove call instead of just remove for func 1.

Signed-off-by: Christian Daudt <csd@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>