[BTI] Update alignment and padding.

guarded_functions and hint_functions have to start at page aligned
addresses and take up at least a page, because mprotect is used to
mark them guarded.

From guarder_functions, the padding was missing. When the code
following it was compiled without BTI, it too ended up guarded,
causing crashes.

The alignment in basic_function.S is not needed. The linker will align
it as necessary.

All the alignments are increased to 16K.

Change-Id: I376889758fe840bac89b4cb205a982e441e6cd6a