ARM: pxa: magician: Add support for MAX1587A Vcore regulator

HTC Magician contains a MAX1587A voltage regulator for a Vcore supply.
The Vcore regulation is required for a CPU speed switching. This patch adds
declaration for the max1586 driver.

Notice:

- MAX1587A version does not support the V6 (USIM) output.
- A boost resistor was directly measured for a board_id 0x3a.

Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>