hash: explicit casts for truncation in CRC32c

hash: explicit casts for truncation in CRC32c

In function 'crc32c_sse42_u64_mimic':
rte_hash_crc.h:402:40:
warning: conversion from 'uint64_t' {aka 'long unsigned int'}
to 'uint32_t' {aka 'unsigned int'} may change value [-Wconversion]
  init_val = crc32c_sse42_u32(d.u32[0], init_val);

Fixes: 00bf774bab0b ("hash: add assembly implementation of CRC32 intrinsics")
Cc: stable@dpdk.org
Signed-off-by: Andy Green <andy@warmcat.com>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>