loongarch64: Add optimizations for rot.

Author: yancheng

kernel/loongarch64/KERNEL.LOONGSON2K1000

@@ -49,4 +49,7 @@ DSUMKERNEL  =  dsum_lsx.S
 SASUMKERNEL =  sasum_lsx.S
 DASUMKERNEL =  dasum_lsx.S
 
+SROTKERNEL  =  srot_lsx.S
+DROTKERNEL  =  drot_lsx.S
+
 endif

kernel/loongarch64/KERNEL.LOONGSON3R5

@@ -49,6 +49,9 @@ DSUMKERNEL  =  dsum_lasx.S
 SASUMKERNEL =  sasum_lasx.S
 DASUMKERNEL =  dasum_lasx.S
 
+SROTKERNEL  =  srot_lasx.S
+DROTKERNEL  =  drot_lasx.S
+
 DGEMMKERNEL    = dgemm_kernel_16x4.S
 DGEMMINCOPY    = dgemm_ncopy_16.S
 DGEMMITCOPY    = dgemm_tcopy_16.S