riscv: binman: Fix compilation error

Some platforms may not have any DDR memory below 4G and for such platforms
the TEXT_BASE and LOAD addresses etc are all 64 bit addresses due to
which the u-boot build fails with below error:

u-boot/arch/riscv/dts/binman.dtsi:30.14-25
Value out of range for 32-bit array element
u-boot/arch/riscv/dts/binman.dtsi:43.14-25
Value out of range for 32-bit array element
u-boot/arch/riscv/dts/binman.dtsi:44.15-26
Value out of range for 32-bit array element
FATAL ERROR: Syntax error parsing input tree

Fix by setting the address-cells property to 2 and converting load
addresses to 64 bit values.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Simon Glass <sjg@chromium.org>