mmc: Add module.h include to sdhci-cns3xxx.c

Fixes: drivers/mmc/host/sdhci-cns3xxx.c:110: error: 'THIS_MODULE'
       undeclared here (not in a function)

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Chris Ball <cjb@laptop.org>