boards: arm64: imx8mm: rename boards name to smp and non-smp

1. In order to figure out board name easily for a-core and m-core, add
   a53 suffix in a-core board names.

2. Will support two board configures: one for non-smp and one for smp, both
   of them can boot from uboot command line or load into Jailhouse inmate,
   so remove Jaihouse suffix from board names.

Signed-off-by: Jiafei Pan <Jiafei.Pan@nxp.com>