powerpc/book3e-64: rename interrupt_end_book3e with __end_interrupts

Rename 'interrupt_end_book3e' to '__end_interrupts' so that the symbol
can be used by both book3s and book3e.

Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
[scottwood: edit changelog]
Signed-off-by: Scott Wood <scottwood@freescale.com>