x86/entry: Align SYM_CODE_START() variants

Explicitly align a bunch of commonly called SYM_CODE_START() symbols.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111144.144068841@infradead.org