- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r281073, r281074, r281077, r281200:

Use OF_getencprop over OF_getprop and fdt32_to_cpu. The latter may give
us the wrong data in the failure case if shift was not zero.

Remove the extra copy of uart_fdt_get_clock and uart_fdt_get_shift. While
here also use OF_getencprop in uart_fdt_get_clock.

Move uart_fdt_get_clock and uart_fdt_get_shift to uart_bus_fdt.c, we may
not build uart_cpu_fdt.c in all configs.

Fix uart_fdt_get_clock. It should have been using the cell variable passed
in, not value on the stack.

MFC r279723, r279724:

Define new linker set, UART_FDT_CLASS_AND_DEVICE, for registering full
(class and device) FDT UART. Define second one, UART_FDT_CLASS, for UART
class only.

Move the uart_class definitions and fdt compat data into the individual
uart implementations, and export them using the new linker-set mechanism.

Define new linker set, UART_FDT_CLASS_AND_DEVICE, for registering full
(class and device) FDT UART. Define second one, UART_FDT_CLASS, for UART
class only.

This paves the way for declaring uart_class data and ofw/fdt compat data
with a uart implementation, rather than needing a big global table of
compat data and weak-symbol declarations of every existing implementation.

Differential Revision: https://reviews.freebsd.org/D1992
Submitted by: Michal Meloun