clk: imx: Remove unused helpers

clk: imx: Remove unused helpers

Remove all the helpers that are not referenced anywhere
anymore. Most of them are not clk_hw based. The rest are
passing the device as an argument and were intented for
BLK_CTL driver usage, but that is not the case anymore since
the BLK_CTL is (or will be) implemented outside of CCF.

 - imx_clk_divider2
 - imx_clk_gate2_shared2
 - imx_clk_gate3
 - imx_clk_gate4
 - imx_clk_frac_pll
 - imx_clk_sscg_pll
 - imx_clk_pll14xx
 - imx_clk_pll14xx
 - imx_clk_divider2_flags
 - imx_dev_clk_hw_gate
 - imx_dev_clk_hw_gate_shared
 - imx_clk_gate3_flags
 - imx_clk_gate4_flags
 - imx_dev_clk_hw_mux
 - imx_clk_mux2
 - imx_dev_clk_hw_mux_flags
 - imx8m_clk_composite_flags
 - __imx8m_clk_composite
 - imx8m_clk_composite
 - imx8m_clk_composite_critical

Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Link: https://lore.kernel.org/r/1631521490-17171-2-git-send-email-abel.vesa@nxp.com
Reviewed-by: Stephen Boyd <sboyd@kernel.org>