media: venus: core: Fix mutex destroy in remove

The hfi_destroy function is called too early in remove method. It
destroys a mutex which is used later in the .remove from pmruntime.
Solve the issue by moving hfi_destroy after last usage of the mutex.

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>