accel/ivpu: prevent uninitialized data bug in debugfs

accel/ivpu: prevent uninitialized data bug in debugfs

The simple_write_to_buffer() will only initialize data starting from
the *pos offset so if it's non-zero then the first part of the buffer
uninitialized.  Really, if *pos is non-zero then this code won't work
so just check for that at the start of the function.

Fixes: 320323d2e545 ("accel/ivpu: Add debugfs interface for setting HWS priority bands")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Link: https://patch.msgid.link/ahP24m6Mii9EDL7Q@stanley.mountain