regulator: fan53555: Fix wrong TCS_SLEW_MASK

regulator: fan53555: Fix wrong TCS_SLEW_MASK

The support for TCS4525 regulator has been introduced with a wrong
ramp-rate mask, which has been defined as a logical expression instead
of a bit shift operation.

For clarity, fix it using GENMASK() macro.

Fixes: 914df8faa7d6 ("regulator: fan53555: Add TCS4525 DCDC support")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Link: https://lore.kernel.org/r/20230406171806.948290-4-cristian.ciocaltea@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>