clk: mediatek: mt7622: Move infracfg to clk-mt7622-infracfg.c

clk: mediatek: mt7622: Move infracfg to clk-mt7622-infracfg.c

The infracfg driver cannot be converted to clk_mtk_simple_probe() as
it registers cpumuxes, which is not supported on the common probing
mechanism: for this reason, move it to its own file.
While at it, also convert it to be a platform driver instead; to do
so, also add a .remove() callback for this driver.

During the conversion, error handling was added to the infracfg
probe function.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20230306140543.1813621-27-angelogioacchino.delregno@collabora.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>