at91: drop boot_params and PLAT_PHYS_OFFSET

select ARM_PATCH_PHYS_VIRT
as with ARM_PATCH_PHYS_VIRT you can patch boot_params at runtime or any recent
bootloader will provide a valid atags pointer in r2

as point out by Russell on AT91 we never use XIP
so se do not need PLAT_PHYS_OFFSET

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Patrice Vilchez <patrice.vilchez@atmel.com>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-at91/board-gsia18s.c

@@ -576,7 +576,6 @@ static void __init gsia18s_board_init(void)
 }
 
 MACHINE_START(GSIA18S, "GS_IA18_S")
-	.boot_params	= AT91_SDRAM_BASE + 0x100,
 	.timer		= &at91sam926x_timer,
 	.map_io		= at91sam9260_map_io,
 	.init_early	= gsia18s_init_early,