crypto: Fix HMAC failure

Incorrect HMAC values are generated in following scenarios.

- In case of a single transfer with a packet shorter than the
block size, the HMAC generated is incorrect. This is due to
the "FIRST" bit in AUTH_CFG register not being set.  When calling
HMAC_final for a transfer with a single packet (with no prior HMAC
updates), the "FIRST" and "LAST" bit in AUTH_CFG register needs to
be set. Currently FIRST bit is being cleared incorrectly for all
scenarios.

- In a scenario of a mac key input larger than block size, the key
needs to be hashed. The key hashing operation is crashing. This is
due to a NULL, unintialized pointer to the device handle. This is
fixed by intializing the pointer correctly. Further more, key size
is uninitialized, resulting in corruption of buffer.

Change-Id: Iec736f2130e509fcaf631a2c71c5483514666617
Signed-off-by: Mona Hossain <mhossain@codeaurora.org>