LoongArch: Remove obsolete mentions of vcsr

The `vcsr` only exists in the old hardware design, it isn't used in any
shipped hardware from Loongson-3A5000 on. Both scalar FP and LSX/LASX
instructions use the `fcsr` as their control and status registers now.
For example, the RM control bit in fcsr0 is shared by FP, LSX and LASX
instructions.

Particularly, fcsr16 to fcsr31 are reserved for LSX/LASX now, access to
these registers has no visible effect if LSX/LASX is enabled, and will
cause SXD/ASXD exceptions if LSX/LASX is not enabled.

So, mentions of vcsr are obsolete in the first place (it was just used
for debugging), let's remove them.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Qi Hu <huqi@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/include/asm/fpregdef.h

@@ -48,6 +48,5 @@
 #define fcsr1	$r1
 #define fcsr2	$r2
 #define fcsr3	$r3
-#define vcsr16	$r16
 
 #endif /* _ASM_FPREGDEF_H */

arch/loongarch/include/asm/processor.h

@@ -80,7 +80,6 @@ BUILD_FPR_ACCESS(64)
 
 struct loongarch_fpu {
 	unsigned int	fcsr;
-	unsigned int	vcsr;
 	uint64_t	fcc;	/* 8x8 */
 	union fpureg	fpr[NUM_FPU_REGS];
 };
@@ -161,7 +160,6 @@ struct thread_struct {
 	 */							\
 	.fpu			= {				\
 		.fcsr		= 0,				\
-		.vcsr		= 0,				\
 		.fcc		= 0,				\
 		.fpr		= {{{0,},},},			\
 	},							\

arch/loongarch/kernel/asm-offsets.c

@@ -166,7 +166,6 @@ void output_thread_fpu_defines(void)
 
 	OFFSET(THREAD_FCSR, loongarch_fpu, fcsr);
 	OFFSET(THREAD_FCC,  loongarch_fpu, fcc);
-	OFFSET(THREAD_VCSR, loongarch_fpu, vcsr);
 	BLANK();
 }
 

arch/loongarch/kernel/fpu.S

@@ -146,16 +146,6 @@
 	movgr2fcsr	fcsr0, \tmp0
 	.endm
 
-	.macro sc_save_vcsr base, tmp0
-	movfcsr2gr	\tmp0, vcsr16
-	EX	st.w \tmp0, \base, 0
-	.endm
-
-	.macro sc_restore_vcsr base, tmp0
-	EX	ld.w \tmp0, \base, 0
-	movgr2fcsr	vcsr16, \tmp0
-	.endm
-
 /*
  * Save a thread's fp context.
  */