MLK-21485 imx8qm/qxp: Extend image size for bootaux M4

iMX8 has consective address for TCML and TCMU, so the M4 image size
could exceed the TCML boundary and put its data section in TCMU.

So change the size limitation in bootaux to 256KB to include TCMU.

Signed-off-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
(cherry picked from commit cdc80200841055b949677ae8633c6d64fe0d0985)
1 file changed