UefiCpuPkg: RISC-V: TimerLib: Fix delay function to use 64-bit

The timer compare register is 64-bit so simplifying the delay
function.

Cc: Andrei Warkentin <andrei.warkentin@intel.com>
Signed-off-by: Tuan Phan <tphan@ventanamicro.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>

MdePkg/Include/Register/RiscV64/RiscVImpl.h

@@ -20,6 +20,5 @@
   Name:
 
 #define ASM_FUNC(Name)  _ASM_FUNC(ASM_PFX(Name), .text. ## Name)
-#define RISCV_TIMER_COMPARE_BITS  32
 
 #endif