LoongArch: Fix broken DESC => IE transition for 2.43 branch

LoongArch: Fix broken DESC => IE transition for 2.43 branch

If code compiled with -fPIC -mtls-dialect=desc is linked into a PDE or
PIE, and the code refers to external DSO symbols, we can produce broken
link unit as check_relocs expects DESC => IE transition to happen and
emits a TLS IE entry in the GOT, but a too early "continue" in
relax_section actually jumps over the DESC => IE transition so the code
sequence is unchanged and still expecting a TLS descriptor (instead of
an IE entry) in the GOT.

The bug is already fixed in master branch by commit 5c3d09c1855b
("LoongArch: Optimize the relaxation process") so this fix is only
needed for the 2.43 branch.

Reported-by: Icenowy Zheng <uwu@icenowy.me>
Closes: https://gcc.gnu.org/PR118114
Tested-by: Icenowy Zheng <uwu@icenowy.me>
Signed-off-by: Xi Ruoyao <xry111@xry111.site>