wifi: wilc1000: fix RX buffer OOB-write in wilc_wlan_handle_isr_ext()

In the Linux kernel, the following vulnerability has been resolved: wifi: wilc1000: fix RX buffer OOB-write in wilc_wlan_handle_isr_ext() wilc_wlan_handle_isr_ext() takes the RX transfer size from the device-reported interrupt status register (a 15-bit field shifted left by 2, up to 131068 bytes) and reads that many bytes from the device into rx_buffer, which is only WILC_RX_BUFF_SIZE (96K) large. The wrap check only handles the current offset; the size itself is never compared against the buffer, so a bogus SDIO device can make the driver OOB-write rx_buffer by up to ~32K with data it controls. The oversized transfer also leaves rx_buffer_offset past the end of the buffer, after which the unsigned wrap check stops working and the overflow can repeat. Drop any transfer whose size exceeds the RX buffer, acknowledging the data interrupt and re-arming the RX engine so the bogus frame is discarded and reception can continue. This also restores the rx_buffer_offset <= WILC_RX_BUFF_SIZE invariant the wrap check relies on. This is not expected to change driver behavior in most cases: without this check, an oversized transfer would most likely corrupt neighboring kernel memory instead of completing anyway, and the drop path performs the same interrupt acknowledgment and RX engine re-arming as the normal path, so subsequent transfers are received unaffected. Discovered by Atuin - Automated Vulnerability Discovery Engine.