mmc: sdricoh_cs: Less checks in sdricoh_init_mmc() after, error detection

This issue was detected by using the Coccinelle software.

Two pointer checks could be repeated by the sdricoh_init_mmc() function
during error handling even if the relevant properties can be determined
for the involved variables before by source code analysis.

* This implementation detail could be improved by adjustments
  for jump targets according to the Linux coding style convention.

* Drop an unnecessary initialisation for the variable "mmc" then.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>