entry: Correct 'noinstr' attributes

The noinstr attribute is to be specified before the return type in the
same way 'inline' is used.

Similar cases were recently fixed for x86 in commit 7f6fa101 ("x86:
Correct noinstr qualifiers"), but the generic entry code was based on the
the original version and did not carry the fix over.

Fixes: a5497bab ("entry: Provide generic interrupt entry/exit code")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200725091951.744848-3-mingo@kernel.org