soc: imx91: add empty soc.h

Some drivers need header file soc.h, according to Zephyr SoC Porting Guide
soc.h must be provided for each SoC, so created an empty one.

Signed-off-by: Lei Xu <lei.xu@nxp.com>
Signed-off-by: Jiafei Pan <jiafei.pan@nxp.com>
1 file changed