Change initdram() return type to phys_size_t

This patch changes the return type of initdram() from long int to phys_size_t.
This is required for a couple of reasons: long int limits the amount of dram
to 2GB, and u-boot in general is moving over to phys_size_t to represent the
size of physical memory.  phys_size_t is defined as an unsigned long on almost
all current platforms.

This patch *only* changes the return type of the initdram function (in
include/common.h, as well as in each board's implementation of initdram).  It
does not actually modify the code inside the function on any of the platforms;
platforms which wish to support more than 2GB of DRAM will need to modify
their initdram() function code.

Build tested with MAKEALL for ppc, arm, mips, mips-el. Booted on powerpc
MPC8641HPCN.

Signed-off-by: Becky Bruce <becky.bruce@freescale.com>
diff --git a/cpu/ppc4xx/44x_spd_ddr2.c b/cpu/ppc4xx/44x_spd_ddr2.c
index 5214918..c28fc46 100644
--- a/cpu/ppc4xx/44x_spd_ddr2.c
+++ b/cpu/ppc4xx/44x_spd_ddr2.c
@@ -389,7 +389,7 @@
  *		 banks appropriately. If Auto Memory Configuration is
  *		 not used, it is assumed that no DIMM is plugged
  *-----------------------------------------------------------------------------*/
-long int initdram(int board_type)
+phys_size_t initdram(int board_type)
 {
 	unsigned char iic0_dimm_addr[] = SPD_EEPROM_ADDRESS;
 	unsigned char spd0[MAX_SPD_BYTES];
@@ -3081,7 +3081,7 @@
  * 		banks. The configuration is performed using static, compile-
  *		time parameters.
  *---------------------------------------------------------------------------*/
-long initdram(int board_type)
+phys_size_t initdram(int board_type)
 {
 	/*
 	 * Only run this SDRAM init code once. For NAND booting