misc/pvpanic: Remove some dead-code

misc/pvpanic: Remove some dead-code

'pvpanic_remove()' is referenced only by a 'devm_add_action_or_reset()'
call in 'devm_pvpanic_probe()'. So, we know that its parameter is non-NULL.

Axe the unneeded check to save a few lines of code.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/8e425618f4042a8ab8366be4d34026972e77bd40.1622911768.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>