pinctrl: remove pinctrl/machine.h inclusion from pinctrl/pinconf.h

The change adds explicit inclusion of linux/pinctrl/machine.h header
to the only needed pinctrl-madera-core.c file, and therefore inclusion
of pinctrl/machine.h header from pinctrl/pinconf.h can be removed.

The change is preparatory to a follow-up reversal of commit f07512e6
("pinctrl/pinconfig: add debug interface").

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Cc: Charles Keepax <ckeepax@opensource.cirrus.com>
Reviewed-by Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>