s390: fix compile error with memmove_early() inline assembly

Old gcc versions can't handle a bogus early clobber on a Q constraint:

arch/s390/kernel/early.c: In function 'memmove_early.part.1':
arch/s390/kernel/early.c:432:2: error: '&' constraint used with no register class

Simply remove it to fix this.
Reported-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Fixes: d543a106 ("s390: fix initrd corruptions with gcov/kcov instrumented kernels")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/early.c

@@ -417,7 +417,7 @@ static __init void memmove_early(void *dst, const void *src, size_t n)
 		"	brctg	%[n],0b\n"
 		"1:\n"
 		: [addr] "=&d" (addr),
-		  [psw_pgm_addr] "=&Q" (S390_lowcore.program_new_psw.addr),
+		  [psw_pgm_addr] "=Q" (S390_lowcore.program_new_psw.addr),
 		  [dst] "+&a" (dst), [src] "+&a" (src),  [n] "+d" (n)
 		: [incr] "d" (incr)
 		: "cc", "memory");