arm64: dts: mba8xx: replace 0 with IMX_LPCG_CLK_0 for lpcg indices

arm64: dts: mba8xx: replace 0 with IMX_LPCG_CLK_0 for lpcg indices

Replace the 0 with IMX_LPCG_CLK_0 for LPCG clock indices. Although the
numerical value is identical, the LPCG input is defined as
IMX_LPCG_CLK_<n>, so using the symbolic constant improves clarity and
consistency with the LPCG clock naming convention.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>