sfc: Use ACCESS_ONCE when copying efx_tx_queue::read_count
sfc: Use ACCESS_ONCE when copying efx_tx_queue::read_count

Signed-off-by: Ben Hutchings <0672176982fbc629cc374f31a7a45ae1671abf90@solarflare.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas