x86/entry/64: Use TASK_SIZE_MAX for canonical RIP test

Using shifts to determine if an address is canonical is difficult for
the compiler to optimize when the virtual address width is variable
(LA57 feature) without using inline assembly.  Instead, compare RIP
against TASK_SIZE_MAX.  The only user executable address outside of that
range is the deprecated vsyscall page, which can fall back to using IRET.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20231011224351.130935-3-brgerst@gmail.com