qemu: remove unsupported linker option for RHEL6

RHEL6's native gcc does not support this option and
removing it seems to have no effect.  Remove to
allow compiles on RHEL6.

See openbmc/openbmc#1407 to track removal.

Change-Id: I073efde520740c57d9a5b51c19092dd74f532c1d
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>