Add stub implementations of unused syscalls explicitly

[ia]

• Please check if the PR fulfills these requirements

• The changes have been tested locally
• There are no breaking changes

• What kind of change does this PR introduce?
  Add stub implementations of unused syscalls explicitly.

• What is the current behavior?
  There are missed stub implementations for some syscalls which leads to compile warnings for all target devices except Pinecil (both versions) like these ones:

/usr/lib/gcc/arm-none-eabi/13.1.0/../../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/13.1.0/../../../../arm-none-eabi/lib/thumb/v7-m/nofp/libc_nano.a(libc_a-closer.o): in function `_close_r':
closer.c:(.text._close_r+0xc): warning: _close is not implemented and will always fail
/usr/lib/gcc/arm-none-eabi/13.1.0/../../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/13.1.0/../../../../arm-none-eabi/lib/thumb/v7-m/nofp/libc_nano.a(libc_a-lseekr.o): in function `_lseek_r':
lseekr.c:(.text._lseek_r+0x10): warning: _lseek is not implemented and will always fail
/usr/lib/gcc/arm-none-eabi/13.1.0/../../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/13.1.0/../../../../arm-none-eabi/lib/thumb/v7-m/nofp/libc_nano.a(libc_a-readr.o): in function `_read_r':
readr.c:(.text._read_r+0x10): warning: _read is not implemented and will always fail
/usr/lib/gcc/arm-none-eabi/13.1.0/../../../../arm-none-eabi/bin/ld: /usr/lib/gcc/arm-none-eabi/13.1.0/../../../../arm-none-eabi/lib/thumb/v7-m/nofp/libc_nano.a(libc_a-writer.o): in function `_write_r':
writer.c:(.text._write_r+0x10): warning: _write is not implemented and will always fail

• What is the new behavior (if this is a feature change)?
  Implemented stubs of unused syscalls to make compiler... linker, to be precise, happy.

• Other information:

  • Pinecil & Pinecil2 are not affected since deeply inside in their BSP dirs they either have syscalls implemented as stubs already or actually used for debugging;
  • at first I tried to put related code to BSP_Common.c but it seems this file is never compiled and out of source tree somehow for some reason;
  • can't wait to hear the feedback.

[Ralim]

Thank you