soc: ixp4xx/npe: Fix unused match warning

soc: ixp4xx/npe: Fix unused match warning

The kernel test robot found this inconsistency:

  drivers/soc/ixp4xx/ixp4xx-npe.c:737:34: warning:
  'ixp4xx_npe_of_match' defined but not used [-Wunused-const-variable=]
     737 | static const struct of_device_id ixp4xx_npe_of_match[] = {

This is because the match is enclosed in the of_match_ptr()
which compiles into NULL when OF is disabled and this
is unnecessary.

Fix it by dropping of_match_ptr() around the match.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220626074315.61209-1-linus.walleij@linaro.org'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>