x86: drop bogus Tbyte

Prior to commit 1cb0ab18 ("x86/Intel: restrict suffix derivation")
the Tbyte modifier on the FLDT and FSTPT templates was pointless, as
No_ldSuf would have prevented it being accepted. Due to the special
nature of LONG_DOUBLE_MNEM_SUFFIX said commit, however, has led to these
insns being accepted in Intel syntax mode even when "tbyte ptr" was
present. Restore original behavior by dropping Tbyte there. (Note that
these insns in principle should by marked AT&T syntax only, but since
they haven't been so far we probably shouldn't change that.)