mmc: sdhci: add spin lock for sdhci_set_default_irqs in sdhci_init

mmc: sdhci: add spin lock for sdhci_set_default_irqs in sdhci_init

When use one SDIO wifi which enable the runtime PM feature on i.MX6SX,
we meet system hang. This hang happened during the usdhc runtime resume,
in sdhci_init(), when call the sdhci_set_default_irqs. One interrupt
(SDHCI_INT_CARD_INT) triggered just after the host->ier update and before
the write of register SDHCI_SIGNAL_ENABLE. So in sdhci_irq, it will skip
the call of sdio_signal_irq() because current host->ier do not set the
SDHCI_INT_CARD_INT. So this SDIO wifi interrupt always keep triggered,
let the system stuck in irq handle, can't response any other thread.

This patch add spin lock for the sdhci_set_default_irqs to fix this issue.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/1586941255-9237-1-git-send-email-haibo.chen@nxp.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>