at91: add kernel support for sama7g5 soc

Add kernel support for SAMA7G5 by back-porting mainline kernel patches.
Among SAMA7G5 features could be remembered:
- ARM Cortex-A7
- double data rate multi-port dynamic RAM controller supporting DDR2,
  DDR3, DDR3L, LPDDR2, LPDDR3 up to 533MHz
- peripherals for audio, video processing
- 1 gigabit + 1 megabit Ethernet controllers
- 6 CAN controllers
- trust zone support
- DVFS for CPU
- criptography IPs

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>

target/linux/at91/patches-5.10/201-ARM-at91-pm-do-not-initialize-pdev.patch

@@ -0,0 +1,30 @@
+From 31e25503bbad1fffd29fd074a46bd4858b65304f Mon Sep 17 00:00:00 2001
+From: Claudiu Beznea <claudiu.beznea@microchip.com>
+Date: Thu, 15 Apr 2021 13:49:51 +0300
+Subject: [PATCH 201/247] ARM: at91: pm: do not initialize pdev
+
+There is no need to initialize pdev.
+
+Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
+Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
+Link: https://lore.kernel.org/r/20210415105010.569620-6-claudiu.beznea@microchip.com
+---
+ arch/arm/mach-at91/pm.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
+index e9f9fb410761..96f2be0a53cb 100644
+--- a/arch/arm/mach-at91/pm.c
++++ b/arch/arm/mach-at91/pm.c
+@@ -674,7 +674,7 @@ static int __init at91_pm_backup_init(void)
+ {
+ 	struct gen_pool *sram_pool;
+ 	struct device_node *np;
+-	struct platform_device *pdev = NULL;
++	struct platform_device *pdev;
+ 	int ret = -ENODEV;
+ 
+ 	if (!IS_ENABLED(CONFIG_SOC_SAMA5D2))
+-- 
+2.32.0
+