clk: at91: add PMC pll clocks

This patch adds new at91 pll clock implementation using common clk framework.

The pll clock layout describe the PLLX register layout.
There are four pll clock layouts:
- at91rm9200
- at91sam9g20
- at91sam9g45
- sama5d3

PLL clocks are given characteristics:
- min/max clock source rate
- ranges of valid clock output rates
- values to set in out and icpll fields for each supported output range

These characteristics are checked during rate change to avoid
over/underclocking.

These characteristics are described in atmel's SoC datasheet in
"Electrical Characteristics" paragraph.

Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

include/linux/clk/at91_pmc.h

@@ -164,6 +164,8 @@ extern void __iomem *at91_pmc_base;
 #define		AT91_PMC_CFDEV		(1 << 18)		/* Clock Failure Detector Event [some SAM9] */
 #define	AT91_PMC_IMR		0x6c			/* Interrupt Mask Register */
 
+#define AT91_PMC_PLLICPR	0x80			/* PLL Charge Pump Current Register */
+
 #define AT91_PMC_PROT		0xe4			/* Write Protect Mode Register [some SAM9] */
 #define		AT91_PMC_WPEN		(0x1  <<  0)		/* Write Protect Enable */
 #define		AT91_PMC_WPKEY		(0xffffff << 8)		/* Write Protect Key */