fsi: occ: Use a large buffer for responses

fsi: occ: Use a large buffer for responses

Allocate a large buffer for each OCC to handle response data. This
removes memory allocation during an operation, and also allows for
the maximum amount of SBE FFDC.

Previously for the putsram and attn commands, only 32 words would have
been available, and for getsram, only up to the size of the transfer.
SBE FFDC might be up to 8Kb.

The SBE interface expects data to be specified in units of words (4
bytes), defined as OCC_MAX_RESP_WORDS.

This change allows the full FFDC capture to be implemented, where before
it was not available.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20211019205307.36946-2-eajames@linux.ibm.com
Signed-off-by: Joel Stanley <joel@jms.id.au>