crypto: omap-sham - replace flags operation with atomic bit operations

Some flags are changed in interrupt handlers and verified in the tasklet.
There might be a race condition when tasklet is interrupted or another
cpu/core will run IRQ handler and tasklet in parallel.
Atomic bitops functions are now used instead of bitmask operations.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>