mips: Realtek RTL: select NO_EXCEPT_FILL

The CPUs in these SoCs support MIPS32 R2, and allow ebase relocation.
Even if the default exception base of 0x80000000 is used, the
MIPS_GENERIC load address of 0x80100000 leaves sufficient space to not
need an extra 0x400 bytes of padding.

Suggested-by: Olliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Sander Vanheule <sander@svanheule.net>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>