powerpc: T1040D4RDB: Separate from T1040RDB in Kconfig

Use TARGET_T1040D4RDB in Kconfig to simplify config macros. Replace
CONFIG_T1040D4RDB with TARGET_T1040D4RDB and clean up existing macros.

Signed-off-by: York Sun <york.sun@nxp.com>
11 files changed