linux-user: sparc: Remove unused struct 'target_mc_fq'

This struct is unused since Peter's
Commit b8ae597f0e6d ("linux-user/sparc: Fix errors in target_ucontext
structures")

However, hmm, I'm a bit confused since that commit modifies the
structure and then removes it, was that intentional?

Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

linux-user/sparc/signal.c

@@ -546,11 +546,6 @@ void setup_sigtramp(abi_ulong sigtramp_page)
 typedef abi_ulong target_mc_greg_t;
 typedef target_mc_greg_t target_mc_gregset_t[SPARC_MC_NGREG];
 
-struct target_mc_fq {
-    abi_ulong mcfq_addr;
-    uint32_t mcfq_insn;
-};
-
 /*
  * Note the manual 16-alignment; the kernel gets this because it
  * includes a "long double qregs[16]" in the mcpu_fregs union,