clk: at91: pmc: merge at91_pmc_init in atmel_pmc_probe

at91_pmc_init() doesn't do much anymore, merge it in atmel_pmc_probe().

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>