clk: at91: audio-pll: fix audio pmc type

The allocation for the audio pmc is using the size of struct clk_audio_pad
instead of struct clk_audio_pmc. This works fine because the former is
larger than the latter but it is safer to be correct.

Fixes: ("0865805d clk: at91: add audio pll clock drivers")
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>