timers: Rename next_expiry_recalc() to be unique

next_expiry_recalc is the name of a function as well as the name of a
struct member of struct timer_base. This might lead to confusion.

Rename next_expiry_recalc() to timer_recalc_next_expiry(). No functional
change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/all/20240904-devel-anna-maria-b4-timers-flseep-v1-1-e98760256370@linutronix.de