mmc: mxcmmc: fix return value check of mmcaddhost()
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v4.9.337 by commit 5f35c038c9f4d258b3cf77885a2730f1417d63e7, it was introduced in version v2.6.29 by commit d96be879ff469759af6d7fcebdb66237c18da6f8. For more details please see the references link.