linker: allow symbols to be in a named __noinit section

This adds a new __noinit_named() macro which can be used to
attach named section attributes for symbols. The original
__noinit creates a section attribute with source file name
and a sequential counter. This simply replaces the counter
with the supplied name. This is useful for demand paging
as developers can choose which symbols is pinned memory.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>