drivers: support 64-bit addresses from devicetree for PLIC, MTIMER, UART

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>