RISC-V: Add FIRMWARE_READ_HI definition

SBI v2.0 added another function to SBI PMU extension to read
the upper bits of a counter with width larger than XLEN.

Add the definition for that function.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Clément Léger <cleger@rivosinc.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20240420151741.962500-3-atishp@rivosinc.comSigned-off-by: Anup Patel <anup@brainfault.org>

arch/riscv/include/asm/sbi.h

@@ -131,6 +131,7 @@ enum sbi_ext_pmu_fid {
 	SBI_EXT_PMU_COUNTER_START,
 	SBI_EXT_PMU_COUNTER_STOP,
 	SBI_EXT_PMU_COUNTER_FW_READ,
+	SBI_EXT_PMU_COUNTER_FW_READ_HI,
 };
 
 union sbi_pmu_ctr_info {