drivers: sdhc: sdhc_spi: rework CMD12 failure logic

Rework CMD12 failure logic for SDHC SPI driver. Previously, the error
code of CMD12 was not checked, so even if CMD12 failed to send the
initial command would be retried. Change this behavior to retry CMD12
until it succeeds. If CMD12 fails, its error code will be propagated to
the caller. Otherwise, the return code from the command being sent by
the caller will be propagated.

Fixes #72365

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>