x86: fix emulation of indirect far calls and jumps

x86: fix emulation of indirect far calls and jumps

Commit 86781624 ("x86_emulate: PUSH <mem> must read source operand
just once") corrected the operands of those of the operations of opcode
extension group 5 that only read memory from SrcMem to DstMem, but
failed to also switch the use of "dst" here to "src".

Reported-by: Anthony Perard <anthony.perard@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Anthony Perard <anthony.perard@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>