net: stmmac: dwmac-meson8b: Avoid cast to incompatible function type

Rather than casting clk_disable_unprepare to an incompatible function
type provide a trivial wrapper with the correct signature for the
use-case.

Reported by clang-16 with W=1:

 drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c:276:6: error: cast from 'void (*)(struct clk *)' to 'void (*)(void *)' converts to incompatible function type [-Werror,-Wcast-function-type-strict]
                                        (void(*)(void *))clk_disable_unprepare,
                                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
No functional change intended.
Compile tested only.

Signed-off-by: Simon Horman <horms@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20230418-dwmac-meson8b-clk-cb-cast-v1-1-e892b670cbbb@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>