init: open /initrd.image with O_LARGEFILE

If initrd data is larger than 2Gb, we'll eventually fail to write to the
/initrd.image file when we hit that limit, unless O_LARGEFILE is set.

Link: https://lkml.kernel.org/r/20240317221522.896040-1-jsperbeck@google.com
Signed-off-by: John Sperbeck <jsperbeck@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>