powerpc/time: Rename mftbl() to mftb()

On PPC64, we have mftb().
On PPC32, we have mftbl() and an #define mftb() mftbl().

mftb() and mftbl() are equivalent, their purpose is to read the
content of SPRN_TRBL, as returned by 'mftb' simplified instruction.

binutils seems to define 'mftbl' instruction as an equivalent
of 'mftb'.

However in both 32 bits and 64 bits documentation, only 'mftb' is
defined, and when performing a disassembly with objdump, the displayed
instruction is 'mftb'

No need to have two ways to do the same thing with different
names, rename mftbl() to have only mftb().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/94dc68d3d9ef9eb549796d4b938b6ba0305a049b.1601556145.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/reg.h

@@ -1439,19 +1439,18 @@ static inline void msr_check_and_clear(unsigned long bits)
 #else /* __powerpc64__ */
 
 #if defined(CONFIG_PPC_8xx)
-#define mftbl()		({unsigned long rval;	\
+#define mftb()		({unsigned long rval;	\
 			asm volatile("mftbl %0" : "=r" (rval)); rval;})
 #define mftbu()		({unsigned long rval;	\
 			asm volatile("mftbu %0" : "=r" (rval)); rval;})
 #else
-#define mftbl()		({unsigned long rval;	\
+#define mftb()		({unsigned long rval;	\
 			asm volatile("mfspr %0, %1" : "=r" (rval) : \
 				"i" (SPRN_TBRL)); rval;})
 #define mftbu()		({unsigned long rval;	\
 			asm volatile("mfspr %0, %1" : "=r" (rval) : \
 				"i" (SPRN_TBRU)); rval;})
 #endif
-#define mftb()		mftbl()
 #endif /* !__powerpc64__ */
 
 #define mttbl(v)	asm volatile("mttbl %0":: "r"(v))

arch/powerpc/include/asm/time.h

@@ -47,7 +47,7 @@ struct div_result {
 
 static inline unsigned long get_tbl(void)
 {
-	return mftbl();
+	return mftb();
 }
 
 static inline unsigned int get_tbu(void)