Clang warns when one enumerated type is implicitly converted to another:

drivers/pinctrl/bcm/pinctrl-bcm2835.c:707:40: warning: implicit
conversion from enumeration type 'enum bcm2835_pinconf_param' to
different enumeration type 'enum pin_config_param' [-Wenum-conversion]
        configs[0] = pinconf_to_config_packed(BCM2835_PINCONF_PARAM_PULL, pull);
                     ~~~~~~~~~~~~~~~~~~~~~~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.

It is expected that pinctrl drivers can extend pin_config_param because
of the gap between PIN_CONFIG_END and PIN_CONFIG_MAX so this conversion
isn't an issue. Most drivers that take advantage of this define the
PIN_CONFIG variables as constants, rather than enumerated values. Do the
same thing here so that Clang no longer warns.
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>