clk: at91: Silence warnings and cleanup __init/extern usage

clk: at91: Silence warnings and cleanup __init/extern usage

Remove useless ifdefs around function prototypes to silence the
following sparse warnings when the configs aren't enabled.

drivers/clk/at91/clk-h32mx.c:95:13: warning: symbol
'of_sama5d4_clk_h32mx_setup' was not declared. Should it be
static?
drivers/clk/at91/clk-utmi.c:159:13: warning: symbol
'of_at91sam9x5_clk_utmi_setup' was not declared. Should it be
static?

Plus, using __init and extern in function prototypes doesn't do
anything, so just drop it throughout this file.

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