mmc: usdhi6rol0: handle NULL data in timeout

mmc: usdhi6rol0: handle NULL data in timeout

BugLink: http://bugs.launchpad.net/bugs/1553179
commit 05caee939f8d58d81e962071da85761e1e3a4c73 upstream.

Commit bb08a7d489bd ("mmc: usdhi6rol0: fix NULL pointer deref in debug
print") fixed one NULL pointer dereference but unfortunately introduced
another.  "data" may be NULL if this is a command timeout for a command
without any data, so we should only use it if we're actually waiting for
data.

Fixes: bb08a7d489bd ("mmc: usdhi6rol0: fix NULL pointer deref in debug print")
Signed-off-by: Rabin Vincent <rabin.vincent@axis.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>