If neither a "hif_mspi" nor "mspi" resource is present, the driver will
just early exit in probe but still return success. Apart from not doing
anything meaningful, this would then also lead to a null pointer access
on removal, as platform_get_drvdata() would return NULL, which it would
then try to dereference when trying to unregister the spi master.

Fix this by unconditionally calling devm_ioremap_resource(), as it can
handle a NULL res and will then return a viable ERR_PTR() if we get one.

The "return 0;" was previously a "goto qspi_resource_err;" where then
ret was returned, but since ret was still initialized to 0 at this place
this was a valid conversion in 63c5395b ("spi: bcm-qspi: Fix
use-after-free on unbind"). The issue was not introduced by this commit,
only made more obvious.

Fixes: fa236a7e ("spi: bcm-qspi: Add Broadcom MSPI driver")
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Reviewed-by: Kamal Dasu <kamal.dasu@broadcom.com>
Link: https://lore.kernel.org/r/20230629134306.95823-1-jonas.gorski@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>