regulator: fan53555: Add TCS4525 DCDC support

TCS4525 main features:

- 2.7V to 5.5V Input Voltage Range;
- 3MHz Constant Switching Frequency;
- 5A Available Load Current;
- Programmable Output Voltage: 0.6V to 1.4V in 6.25mV Steps;
- PFM/PWM Operation for Optimum Increased Efficiency;

Signed-off-by: Joseph Chen <chenjh@rock-chips.com>
[Ezequiel: Forward port]
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Link: https://lore.kernel.org/r/20210421210338.43819-3-ezequiel@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>