[RISC-V] JIT: Remove src/dst from CORINFO_HELP_ASSIGN_BYREF GC kill set (#111360)

* Remove t3 and t5 from RBM_CALLEE_TRASH_NOGC

Author: tomeksowi

src/coreclr/jit/targetriscv64.h

@@ -139,7 +139,7 @@
   #define REG_WRITE_BARRIER_SRC_BYREF    REG_T5
   #define RBM_WRITE_BARRIER_SRC_BYREF    RBM_T5
 
-  #define RBM_CALLEE_TRASH_NOGC          (RBM_T0|RBM_T1|RBM_T2|RBM_T3|RBM_T4|RBM_T5|RBM_T6|RBM_DEFAULT_HELPER_CALL_TARGET)
+  #define RBM_CALLEE_TRASH_NOGC          (RBM_T0|RBM_T1|RBM_T2|RBM_T4|RBM_T6|RBM_DEFAULT_HELPER_CALL_TARGET)
 
   // Registers killed by CORINFO_HELP_ASSIGN_REF and CORINFO_HELP_CHECKED_ASSIGN_REF.
   #define RBM_CALLEE_TRASH_WRITEBARRIER         (RBM_WRITE_BARRIER_DST|RBM_CALLEE_TRASH_NOGC)
@@ -151,7 +151,7 @@
   #define RBM_CALLEE_TRASH_WRITEBARRIER_BYREF   (RBM_WRITE_BARRIER_DST_BYREF | RBM_WRITE_BARRIER_SRC_BYREF | RBM_CALLEE_TRASH_NOGC)
 
   // Registers no longer containing GC pointers after CORINFO_HELP_ASSIGN_BYREF.
-  // Note that x13 and x14 are still valid byref pointers after this helper call, despite their value being changed.
+  // Note that t3 and t5 are still valid byref pointers after this helper call, despite their value being changed.
   #define RBM_CALLEE_GCTRASH_WRITEBARRIER_BYREF RBM_CALLEE_TRASH_NOGC
 
   // GenericPInvokeCalliHelper VASigCookie Parameter