pwm: lpss: Rename MAX_PWMS --> LPSS_MAX_PWMS

The MAX_PWMS definition is already being used by the PWM core.
Using the same name in the certain driver confuses people
and potentially can clash with it.

Hence, rename it by adding LPSS prefix.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>