Increase BERI boot components section alignment to 16

The .text, .bss, and .data sections claimed 16-byte alignment, but were
only aligned to 8 by the linker script.

Discovered with elfcopy(1) from elftoolchain, which performs validation
absent from the binutils strip(1). ELF tool chain ticket #512.

Reported by: brooks
Reviewed by: brooks
Sponsored by: DARPA, AFRL