[lldb] Fix redundant condition in compression type check (NFC) (#94841)

The `else if` condition for checking `m_compression_type` is redundant
as it matches with a previous `if` condition, making the expression
always false. Reported by cppcheck as a possible cut-and-paste error.

Caught by cppcheck -

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp:543:35:
style: Expression is always false because 'else if' condition matches
previous condition at line 535. [multiCondition]

Fix #91222