transceiver: sigproc: add 12 and 20 tap SSE convolution options
transceiver: sigproc: add 12 and 20 tap SSE convolution options

This sets up SSE optimized options for tap counts of 4 to 20 that
are multiples of 4. Speedup varies from 1.3 to 3.9. SSE3 is required.

    Testing 10000 bursts of size 156 * 2

    Finished 4 SSE in 0.028495 secs
    Finished 4 generic in 0.039303 secs

    Finished 8 SSE in 0.031153 secs
    Finished 8 generic in 0.064673 secs

    Finished 12 SSE in 0.036077 secs
    Finished 12 generic in 0.089671 secs

    Finished 16 SSE in 0.042359 secs
    Finished 16 generic in 0.143284 secs

    Finished 20 SSE in 0.042645 secs
    Finished 20 generic in 0.168347 secs

Signed-off-by: Thomas Tsou <7360a69f2d05d24df84c29f24b488ef8cc0e7ae2@vt.edu>

0x7678/openbts-multi-arfcn,0x7678/openbts-multi-arfcn,0x7678/openbts-multi-arfcn,0x7678/openbts-multi-arfcn,0x7678/openbts-multi-arfcn