qup_i2c: Correct free memory call

Correct freeing of memory, which is allocated using
the devm prefixed API, to free it using devm_kfree rather
then kfree.

CRs-Fixed: 582597
Change-Id: If1aa9bcd86bb3a7d35adc5630ff19ad08bbdf762
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>