RISC-V: drop a needless check in print_isa_ext()

isa_ext_arr cannot be empty, as some of the extensions within it are
always built into the kernel. When this code was first added, back in
commit a9b20260 ("RISC-V: Improve /proc/cpuinfo output for ISA
extensions"), the array was empty and needed a dummy item & thus there
could be no extensions present. When the first multi-letter ones did
get added, it was Sscofpmf - which didn't have a Kconfig symbol to
disable it.

Remove this check, as it has been redundant since Sscofpmf was added.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-veggie-mug-3d3bf6787ae2@wendySigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/kernel/cpu.c

@@ -237,10 +237,6 @@ static void print_isa_ext(struct seq_file *f)
 
 	arr_sz = ARRAY_SIZE(isa_ext_arr) - 1;
 
-	/* No extension support available */
-	if (arr_sz <= 0)
-		return;
-
 	for (i = 0; i <= arr_sz; i++) {
 		edata = &isa_ext_arr[i];
 		if (!__riscv_isa_extension_available(NULL, edata->isa_ext_id))