When neither LANTIQ nor MIPS_MALTA is set, 'physical_memsize' is not
declared. This causes the build to fail with:

mips-linux-ld: arch/mips/kernel/vpe-mt.o: in function `vpe_run':
arch/mips/kernel/vpe-mt.c:(.text.vpe_run+0x280): undefined reference to `physical_memsize'

LANTIQ is not using 'physical_memsize' and MIPS_MALTA's use of it is
self-contained in mti-malta/malta-dtshim.c.
Use of physical_memsize in vpe-mt.c appears to be unused, so eliminate
this loader mode completely and require VPE programs to be compiled with
DFLT_STACK_SIZE and DFLT_HEAP_SIZE defined.

Fixes: 9050d50e ("MIPS: lantiq: Set physical_memsize")
Fixes: 1a2a6d7e ("MIPS: APRP: Split VPE loader into separate files.")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/all/202302030625.2g3E98sY-lkp@intel.com/
Cc: Dengcheng Zhu <dzhu@wavecomp.com>
Cc: John Crispin <john@phrozen.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Philippe Mathieu-Daudé <philmd@linaro.org>
Cc: "Steven J. Hill" <Steven.Hill@imgtec.com>
Cc: Qais Yousef <Qais.Yousef@imgtec.com>
Cc: Yang Yingliang <yangyingliang@huawei.com>
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>