I used (uint64_t) cast to avoid "right shift count >= width of type"
warning.  <linux/kernel.h> provides nice helpers to cater to it.
The code will be cleaner, and easier to understand.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>