MIPS: Alchemy: Remove direct access to prepare_count field of struct clk

MIPS: Alchemy: Remove direct access to prepare_count field of struct clk

Replacing it with a call to __clk_is_prepared(), which isn't entirely
equivalent but in practice shouldn't matter.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8120/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>