x86-64: allow HLE store of accumulator to absolute 32-bit address

In commit 1212781b ("ix86: allow HLE store of accumulator to
absolute address") I was wrong to exclude 64-bit code. Dropping the
check also leads to better diagnostics in 64-bit code ("MOV", after
all, isn't invalid with "XRELEASE").

While there also limit the amount of further checks done: The operand
type checks that were there were effectively redundant with other ones
anyway, plus it's quite fine to also have "xrelease mov <disp>, %eax"
look for the next MOV template (in fact again also improving
diagnostics).