brcmfmac: pcie: Fix crashes due to early IRQs

The driver was enabling IRQs before the message processing was
initialized. This could cause IRQs to come in too early and crash the
driver. Instead, move the IRQ enable and hostready to a bus preinit
function, at which point everything is properly initialized.

Fixes: 9e37f045

 ("brcmfmac: Adding PCIe bus layer support.")
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Cc: stable@vger.kernel.org
Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220131160713.245637-7-marcan@marcan.st