i2c: davinci: fix PM disable depth imbalance in davinci_i2c_probe

The pm_runtime_enable will increase power disable depth. Thus a
pairing decrement is needed on the error handling path to keep
it balanced according to context.

Fixes: 17f88151 ("i2c: davinci: Add PM Runtime Support")
Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
Reviewed-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Wolfram Sang <wsa@kernel.org>