powerpc/32s: get rid of CPU_FTR_601 feature

Now that 601 is exclusive from other 6xx, CPU_FTR_601 and
associated fixups are useless.

Drop this feature and use #ifdefs instead.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ecdb7194a17dbfa01865df6a82979533adc2c70b.1566834712.git.christophe.leroy@c-s.fr

arch/powerpc/include/asm/timex.h

@@ -17,38 +17,10 @@ typedef unsigned long cycles_t;
 
 static inline cycles_t get_cycles(void)
 {
-#ifdef __powerpc64__
+	if (IS_ENABLED(CONFIG_BOOK3S_601))
+		return 0;
+
 	return mftb();
-#else
-	cycles_t ret;
-
-	/*
-	 * For the "cycle" counter we use the timebase lower half.
-	 * Currently only used on SMP.
-	 */
-
-	ret = 0;
-
-	__asm__ __volatile__(
-#ifdef CONFIG_PPC_8xx
-		"97:	mftb %0\n"
-#else
-		"97:	mfspr %0, %2\n"
-#endif
-		"99:\n"
-		".section __ftr_fixup,\"a\"\n"
-		".align 2\n"
-		"98:\n"
-		"	.long %1\n"
-		"	.long 0\n"
-		"	.long 97b-98b\n"
-		"	.long 99b-98b\n"
-		"	.long 0\n"
-		"	.long 0\n"
-		".previous"
-		: "=r" (ret) : "i" (CPU_FTR_601), "i" (SPRN_TBRL));
-	return ret;
-#endif
 }
 
 #endif	/* __KERNEL__ */