jump_label: Avoid unneeded casts in STATIC_KEY_INIT_{TRUE,FALSE}

Commit 3821fd35 ("jump_label: Reduce the size of struct static_key")
introduced the union to struct static_key.

It is more natual to set JUMP_TYPE_* to the .type field without casting.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220213165717.2354046-1-masahiroy@kernel.org