drivers: ddr: altera: Fix integer overflow during size calculation

drivers: ddr: altera: Fix integer overflow during size calculation

Data structure, dramaddrw, is defined as u32. Compiler performs
32-bit arithmetic and logic operations on this data structure. Fix
is provided to avoid integer overflow while performing shifting
operations greater than 32-bit.

Signed-off-by: Naresh Kumar Ravulapalli <nareshkumar.ravulapalli@altera.com>
Reviewed-by: Tien Fong Chee <tien.fong.chee@altera.com>