genirq/matrix: Remove redundant assignment to variable 'end'

Variable end is being initialized with a value that is never read, it
is being re-assigned later with the same value. The initialization is
redundant and can be removed.

Cleans up clang scan build warning:
kernel/irq/matrix.c:289:25: warning: Value stored to 'end' during its
initialization is never read [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20220422110418.1264778-1-colin.i.king@gmail.com