imx: mx6: display max cpu frequency in print_cpuinfo()

Display the max CPU frequency as well as the current running CPU frequency
if the max CPU frequency is available and differs from the current CPU
frequency.

Before:
CPU:   Freescale i.MX6Q rev1.2 at 792 MHz

After - using an 800MHz IMX6DL (running at its max)
CPU:   Freescale i.MX6DL rev1.1 at 792 MHz

After - using a 1GHz IMX6Q (not running at its max):
CPU:   Freescale i.MX6Q rev1.2 996 MHz (running at 792 MHz)

Cc: Stefan Roese <sr@denx.de>
Cc: Eric Nelson <eric.nelson@boundarydevices.com>
Cc: Heiko Schocher <hs@denx.de>
Cc: Nikita Kiryanov <nikita@compulab.co.il>
Cc: Jon Nettleton <jon.nettleton@gmail.com>
Cc: Jason Liu <r64343@freescale.com>
Cc: Ye Li <b37916@freescale.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: Markus Niebel <Markus.Niebel@tq-group.com>
Cc: Peng Fan <b51431@freescale.com>
Tested-by: Nikolay Dimitrov <picmaster@mail.bg>
Signed-off-by: Tim Harvey <tharvey@gateworks.com>

arch/arm/imx-common/cpu.c

@@ -144,7 +144,7 @@ const char *get_imx_type(u32 imxtype)
 
 int print_cpuinfo(void)
 {
-	u32 cpurev;
+	u32 cpurev, max_freq;
 
 #if defined(CONFIG_MX6) && defined(CONFIG_IMX6_THERMAL)
 	struct udevice *thermal_dev;
@@ -153,11 +153,25 @@ int print_cpuinfo(void)
 
 	cpurev = get_cpu_rev();
 
+#if defined(CONFIG_MX6)
+	printf("CPU:   Freescale i.MX%s rev%d.%d",
+	       get_imx_type((cpurev & 0xFF000) >> 12),
+	       (cpurev & 0x000F0) >> 4,
+	       (cpurev & 0x0000F) >> 0);
+	max_freq = get_cpu_speed_grade_hz();
+	if (!max_freq || max_freq == mxc_get_clock(MXC_ARM_CLK)) {
+		printf(" at %dMHz\n", mxc_get_clock(MXC_ARM_CLK) / 1000000);
+	} else {
+		printf(" %d MHz (running at %d MHz)\n", max_freq / 1000000,
+		       mxc_get_clock(MXC_ARM_CLK) / 1000000);
+	}
+#else
 	printf("CPU:   Freescale i.MX%s rev%d.%d at %d MHz\n",
 		get_imx_type((cpurev & 0xFF000) >> 12),
 		(cpurev & 0x000F0) >> 4,
 		(cpurev & 0x0000F) >> 0,
 		mxc_get_clock(MXC_ARM_CLK) / 1000000);
+#endif
 
 #if defined(CONFIG_MX6) && defined(CONFIG_IMX6_THERMAL)
 	ret = uclass_get_device(UCLASS_THERMAL, 0, &thermal_dev);