sched/core: Combine separate 'else' and 'if' statements

sched/core: Combine separate 'else' and 'if' statements

The kernel coding style recommends using 'else if' instead of
placing 'if' on a separate line after 'else'. This change makes
the code consistent with the rest of the kernel codebase.

Signed-off-by: Liang Luo <luoliang@kylinos.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260608071842.325159-1-luoliang@kylinos.cn