Implement architecture-specific ELF header definitions and relocation handling
for the MIPS architecture to enable loadable modules.
Fixes#19178.
Changes include:
- Add `arch/mips/include/elf.h` with MIPS ELF relocation types and
architecture-specific ELF data structures (`arch_elfdata_s`).
- Implement `libs/libc/machine/mips/arch_elf.c` containing `up_checkarch`,
`up_relocate`, and `up_relocateadd` functions handling `R_MIPS_NONE`,
`R_MIPS_32`, `R_MIPS_26`, `R_MIPS_HI16`, and `R_MIPS_LO16` relocations.
- Integrate MIPS machine-specific C library support in
`libs/libc/machine/mips/Make.defs`.
- Update `LDMODULEFLAGS` in `arch/mips/src/mips32/Toolchain.defs` to include the
little-endian (`-EL`) flag.
- Update `up_coherent_dcache` for proper cache synchronization on JZ4780.
Signed-off-by: Lwazi Dube <lwazeh@gmail.com>
