powerpc/sstep: Remove empty if statement checking for invalid form

The check should be performed by the caller. This fixes a compile
error with W=1.

../arch/powerpc/lib/sstep.c: In function ‘mlsd_8lsd_ea’:
../arch/powerpc/lib/sstep.c:225:3: error: suggest braces around empty body in an ‘if’ statement [-Werror=empty-body]
   ; /* Invalid form. Should already be checked for by caller! */
   ^
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914211007.2285999-4-clg@kaod.org

arch/powerpc/lib/sstep.c

@@ -219,10 +219,13 @@ static nokprobe_inline unsigned long mlsd_8lsd_ea(unsigned int instr,
 		ea += regs->gpr[ra];
 	else if (!prefix_r && !ra)
 		; /* Leave ea as is */
-	else if (prefix_r && !ra)
+	else if (prefix_r)
 		ea += regs->nip;
-	else if (prefix_r && ra)
-		; /* Invalid form. Should already be checked for by caller! */
+
+	/*
+	 * (prefix_r && ra) is an invalid form. Should already be
+	 * checked for by caller!
+	 */
 
 	return ea;
 }