mpt2sas: Added Reply Descriptor Post Queue (RDPQ) Array support

mpt2sas: Added Reply Descriptor Post Queue (RDPQ) Array support

Up to now, Driver allocates a single contiguous block of memory
pool for all reply queues and passes down a single address in the
ReplyDescriptorPostQueueAddress field of the IOC Init Request
Message to the firmware.

When firmware receives this address, it will program each of the
Reply Descriptor Post Queue registers, as each reply queue has its
own register. Thus the firmware, starting from a base address it
determines the starting address of the subsequent reply queues
through some simple arithmetic calculations.

The size of this contiguous block of memory pool is directly proportional
to number of MSI-X vectors and the HBA queue depth. For example higher
MSIX vectors requires larger contiguous block of memory pool.

But some of the OS kernels are unable to allocate this larger
contiguous block of memory pool.

So, the proposal is to allocate memory independently for each
Reply Queue and pass down all of the addresses to the firmware.
Then the firmware will just take each address and program the value
into the correct register.

When HBAs with older firmware(i.e. without RDPQ capability) is used
with this new driver then the max_msix_vectors value would be set
to 8 by default.

Change_set in v1:

1. Declared _base_get_ioc_facts() function at the beginning of the mpt2sas_base.c
file instead of moving all these functions before mpt2sas_base_map_resources() function
        a. _base_wait_for_doorbell_int()
        b. _base_wait_for_doorbell_ack()
        c. _base_wait_for_doorbell_not_used()
        d. _base_handshake_req_reply_wait()
        e. _base_get_ioc_facts()

2. Initially set the consistent DMA mask to 32 bit and then change it to 64 bit mask
after allocating RDPQ pools by calling the function _base_change_consistent_dma_mask.
This is to ensure that all the upper 32 bits of RDPQ entries's base address to be same.

3. Reduced the redundancy between the RDPQ and non-RDPQ support in these following functions
        a. _base_release_memory_pools()
        b. _base_allocate_memory_pools()
        c. _base_send_ioc_init()
        d. _base_make_ioc_operational()

Signed-off-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>