clk: bcm2835: remove use of BCM2835_CLOCK_COUNT in driver

As the use of BCM2835_CLOCK_COUNT in
include/dt-bindings/clock/bcm2835.h is frowned upon as
it needs to get modified every time a new clock gets introduced
this patch changes the clk-bcm2835 driver to use a different
scheme for registration of clocks and pll, so that there
is no more need for BCM2835_CLOCK_COUNT to be defined.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>