clk: Constify struct clk_bulk_data * where possible

clk: Constify struct clk_bulk_data * where possible

The following functions:

    - clk_bulk_enable()
    - clk_bulk_prepare()
    - clk_bulk_disable()
    - clk_bulk_unprepare()

already expect const clk_bulk_data * as a second parameter, however
their no-op version have mismatching prototypes that don't. Fix that.

While at it, constify the second argument of clk_bulk_prepare_enable()
and clk_bulk_disable_unprepare(), since the functions they are
comprised of already accept const clk_bulk_data *.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Chris Healy <cphealy@gmail.com>
Cc: linux-clk@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: https://lkml.kernel.org/r/20190717145651.17250-1-andrew.smirnov@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>