Add some comments to clocks in atstk1002.h

This patch applies some clarifying comments to how the different
clocks are setup according to atstk1002.h Some of the previous
comments where stating wrongful information.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

include/configs/atstk1002.h

@@ -39,8 +39,10 @@
 #define CFG_HZ				1000
 
 /*
- * Set up the PLL to run at 199.5 MHz, the CPU to run at 1/2 the PLL
- * frequency and the peripherals to run at 1/4 the PLL frequency.
+ * Set up the PLL to run at 140 MHz, the CPU to run at the PLL
+ * frequency, the HSB and PBB at 1/2, and the PBA to run at 1/4 the
+ * PLL frequency.
+ * (CFG_OSC0_HZ * CFG_PLL0_MUL) / CFG_PLL0_DIV = PLL MHz
  */
 #define CONFIG_PLL			1
 #define CFG_POWER_MANAGER		1
@@ -48,9 +50,25 @@
 #define CFG_PLL0_DIV			1
 #define CFG_PLL0_MUL			7
 #define CFG_PLL0_SUPPRESS_CYCLES	16
+/*
+ * Set the CPU running at:
+ * PLL / (2^CFG_CLKDIV_CPU) = CPU MHz
+ */
 #define CFG_CLKDIV_CPU			0
+/*
+ * Set the HSB running at:
+ * PLL / (2^CFG_CLKDIV_HSB) = HSB MHz
+ */
 #define CFG_CLKDIV_HSB			1
+/*
+ * Set the PBA running at:
+ * PLL / (2^CFG_CLKDIV_PBA) = PBA MHz
+ */
 #define CFG_CLKDIV_PBA			2
+/*
+ * Set the PBB running at:
+ * PLL / (2^CFG_CLKDIV_PBB) = PBB MHz
+ */
 #define CFG_CLKDIV_PBB			1
 
 /*