riscv: cpufeature: detect RISCV_ALTERNATIVES_EARLY_BOOT earlier

Currently riscv_cpufeature_patch_func() does nothing at the
RISCV_ALTERNATIVES_EARLY_BOOT stage. Add a check to detect whether we
are in this stage and exit early. This will allow us to use
riscv_cpufeature_patch_func() for scanning of all ISA extensions.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230128172856.3814-3-jszhang@kernel.orgSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/kernel/cpufeature.c

@@ -330,6 +330,9 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
 	struct alt_entry *alt;
 	u32 tmp;
 
+	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
+		return;
+
 	for (alt = begin; alt < end; alt++) {
 		if (alt->vendor_id != 0)
 			continue;