wifi: wilc1000: add 'isinit' flag for SDIO bus similar to SPI

Similar to SPI priv data, add 'isinit' variable in SDIO priv. Make use
of the state to invoke hif_init() once, and acquire the lock before
accessing hif function.

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220720160302.231516-7-ajay.kathat@microchip.com