powerpc: Remove mfvtb()

This function is only used by get_vtb(). They are almost the same except
the reading from the real register. Move the mfspr() to get_vtb() and
kill the function mfvtb(). With this, we can eliminate the use of
cpu_has_feature() in very core header file like reg.h. This is a
preparation for the use of jump label for cpu_has_feature().

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/reg.h

@@ -1256,15 +1256,6 @@ static inline void msr_check_and_clear(unsigned long bits)
 		__msr_check_and_clear(bits);
 }
 
-static inline unsigned long mfvtb (void)
-{
-#ifdef CONFIG_PPC_BOOK3S_64
-	if (cpu_has_feature(CPU_FTR_ARCH_207S))
-		return mfspr(SPRN_VTB);
-#endif
-	return 0;
-}
-
 #ifdef __powerpc64__
 #if defined(CONFIG_PPC_CELL) || defined(CONFIG_PPC_FSL_BOOK3E)
 #define mftb()		({unsigned long rval;				\

arch/powerpc/include/asm/time.h

@@ -103,7 +103,7 @@ static inline u64 get_vtb(void)
 {
 #ifdef CONFIG_PPC_BOOK3S_64
 	if (cpu_has_feature(CPU_FTR_ARCH_207S))
-		return mfvtb();
+		return mfspr(SPRN_VTB);
 #endif
 	return 0;
 }