Usage of 64-bit address constants from devicetree without
an UINT64_C wrapping macro results in the following warning
and the cut-off of the address value:
"warning: integer constant is so large that it is unsigned"
This change fixes such issue for PLIC, MTIMER and UART in case
they are used with some 64-bit RISC-V platforms
Signed-off-by: Alexander Razinkov <alexander.razinkov@syntacore.com>