[ELF] Refine LMA offset propagation rule in D76995

If neither AT(lma) nor AT>lma_region is specified,
D76995 keeps `lmaOffset` (LMA - VMA) if the previous section is in the
default LMA region.

This patch additionally checks that the two sections are in the same
memory region.

Add a test case derived from https://bugs.llvm.org/show_bug.cgi?id=45313

  .mdata : AT(0xfb01000) { *(.data); } > TCM
  // It is odd to make .bss inherit lmaOffset, because the two sections
  // are in different memory regions.
  .bss : { *(.bss) } > DDR

With this patch, section VMA/LMA match GNU ld. Note, GNU ld supports
out-of-order (w.r.t sh_offset) sections and places .text and .bss in the
same PT_LOAD. We don't have that behavior.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D81986