NFC: set info->ram_patch to NULL when it is released

When info->ram_patch is released info->otp_patch is being set
to NULL rather than info->ram_patch. I believe this is a cut-n-paste
bug from almost identical code proceeding it that uses the same
idiom for info->otp_patch.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>