mmc: card: mmc_test: Simplify a trivial if-return sequence

Simplify a trivial if-return sequence. Possibly combine with a
preceding function call.

The semantic patch that makes this change is available
in scripts/coccinelle/misc/simple_return.cocci.

More information about semantic patching is available at
http://coccinelle.lip6.fr/



Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>