pinctrl: mlxbf3: set varaiable mlxbf3_pmx_funcs storage-class-specifier to static

smatch reports
drivers/pinctrl/pinctrl-mlxbf3.c:162:20: warning: symbol
  'mlxbf3_pmx_funcs' was not declared. Should it be static?

This variable is only used in one file so it should be static.

Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20230404004501.1913144-1-trix@redhat.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>