crypto: inside-secure - Made locally used safexcel_pci_remove() static

safexcel_pci_remove() is only used locally in the module and not exported,
so added a static function specifier.
This fixes a sparse issue reported by Ben Dooks.

Fixes: 625f269a ("crypto: inside-secure - add support for...")
Signed-off-by: Pascal van Leeuwen <pvanleeuwen@verimatrix.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>