clk: bcm2835: remove remains from stub clk driver

This commit removes the fixed clocks introduced as a stub clock driver
added with commit 75fabc3f ("ARM: bcm2835: add stub clock driver").
Originally they were used to drive the AMBA bus and PL011 uart driver.
Now these clocks are derived by the CPRMAN clock driver and configured
in DT.

Additionally, get rid of init_machine function in bcm2835 board file
as there's nothing to do any longer.

Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Acked-by: Eric Anholt <eric@anholt.net>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>