net: atheros: atl1c: remove unused atl1c_irq_reset function

clang with W=1 reports
drivers/net/ethernet/atheros/atl1c/atl1c_main.c:214:20: error:
  unused function 'atl1c_irq_reset' [-Werror,-Wunused-function]
static inline void atl1c_irq_reset(struct atl1c_adapter *adapter)
                   ^
This function is not used, so remove it.

Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://lore.kernel.org/r/20230320232317.1729464-1-trix@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>