cmd: cpu: fix NULL cpu feature prints

Commit 740d5d34 added two new features but only one feature name,
which results in NULL prints when device_id feature is selected.

Before:
	HG556a # cpu detail
	 -1: cpu@0	BCM6358A1
		ID = 0, freq = 300 MHz: L1 cache, MMU, NULL
		Device ID 0x2a010
	 -1: cpu@1	BCM6358A1
		ID = 1, freq = 300 MHz: L1 cache, MMU, NULL
		Device ID 0x2a010
After:
	HG556a # cpu detail
	 -1: cpu@0	BCM6358A1
		ID = 0, freq = 300 MHz: L1 cache, MMU, Device ID
		Device ID 0x2a010
	 -1: cpu@1	BCM6358A1
		ID = 1, freq = 300 MHz: L1 cache, MMU, Device ID
		Device ID 0x2a010
Signed-off-by: NÁlvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>
Reviewed-by: NTom Rini <trini@konsulko.com>

cmd/cpu.c

@@ -15,6 +15,7 @@ static const char *cpu_feature_name[CPU_FEAT_COUNT] = {
 	"L1 cache",
 	"MMU",
 	"Microcode",
+	"Device ID",
 };
 
 static int print_cpu_list(bool detail)