linux-qoriq-sdk: enable autofs kernel config

Autofs is required by proc-sys-fs-binfmt_misc.automount service which is
currently failing for PPC targets.

JIRA: http://jira.alm.mentorg.com:8080/browse/SB-3245

Signed-off-by: Fahad Usman <fahad_usman@mentor.com>
Merge pull request #268 from fahadusman/sb-3245

linux-qoriq-sdk: enable autofs kernel config