x86/boot: Remove redundant initialization of the 'delta' variable in strcmp()

The 'delta' variable is zero-initialized, but never
read before the real initialization happens.

The assignment is redundant and can be removed.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231219141304.367200-1-colin.i.king@gmail.com