clk: imx8mp: Remove IPG_AUDIO_ROOT from imx8mp-clock.h

Since the commit b24e288d ("clk: imx: Remove the audio ipg clock
from imx8mp") removes the non-existing IPG_AUDIO_ROOT from the
clk-imx8mp.c, and this definition is not used by anywhere, let us
removed it in the imx8mp-clock.h as well.
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Link: https://lore.kernel.org/r/20211109125657.63485-1-hui.wang@canonical.comSigned-off-by: Abel Vesa <abel.vesa@nxp.com>

include/dt-bindings/clock/imx8mp-clock.h

@@ -117,7 +117,6 @@
 #define IMX8MP_CLK_AUDIO_AHB			108
 #define IMX8MP_CLK_MIPI_DSI_ESC_RX		109
 #define IMX8MP_CLK_IPG_ROOT			110
-#define IMX8MP_CLK_IPG_AUDIO_ROOT		111
 #define IMX8MP_CLK_DRAM_ALT			112
 #define IMX8MP_CLK_DRAM_APB			113
 #define IMX8MP_CLK_VPU_G1			114