bpf: fix error conversion from long unsigned int to unsigned int [-Werror=overflow]

Regenerating BPF target using the maintainer mode emits:
.../opcodes/bpf-opc.c:57:11: error: conversion from ‘long unsigned int’ to ‘unsigned int’ changes value from ‘18446744073709486335’ to ‘4294902015’ [-Werror=overflow]
  57 |   64, 64, 0xffffffffffff00ff, { { F (F_IMM32) }, { F (F_OFFSET16) }, { F (F_SRCLE) }, { F (F_OP_CODE) }, { F (F_DSTLE) }, { F (F_OP_SRC) }, { F (F_OP_CLASS) }, { 0 } }

The use of a narrow size to handle the mask CGEN in instruction format
is causing this error.  Additionally eBPF `call' instructions
constructed by expressions using symbols (BPF_PSEUDO_CALL) emits
annotations in `src' field of the instruction, used to identify BPF
target endianness.

cpu/
	* bpf.cpu (define-call-insn): Remove `src' field from
	instruction mask.

include/
	*opcode/cge.h (CGEN_IFMT): Adjust mask bit width.

opcodes/
	* bpf-opc.c: Regenerate.