hwmon: (mlxreg-fan) Add support for new flavour of capability register

hwmon: (mlxreg-fan) Add support for new flavour of capability register

FAN platform data is common across the various systems, while fan
driver should be able to apply only the fan instances relevant
to specific system.

For example, platform data might contain descriptions for fan1,
fan2, ..., fan{n}, while some systems equipped with all 'n' fans,
others with less.
Also, on some systems fan drawer can be equipped with several
tachometers and on others only with one.

For detection of the real number of equipped drawers and tachometers
special capability registers are used.
These registers used to indicate presence of drawers and tachometers
through the bitmap.

For some new big modular systems this register will provide presence
data by counter.

Use slot parameter to distinct whether capability register contains
bitmask or counter.

Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20250113084859.27064-3-vadimp@nvidia.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>