clk: bcm2835: Introduce SoC specific clock registration

In order to support SoC specific clocks (e.g. emmc2 for BCM2711), we
extend the description with a SoC support flag. This approach avoids long
and mostly redundant lists of clock IDs. Since PLLH is specific to
BCM2835, we register only rest of the clocks as common to all SoC.

Suggested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Acked-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>