qcacmn: Remove 2.6.19 kernel check from qdf_defer

qdf_defer contains backwards compatibility code for Linux kernel
versions <=2.6.19. At the time of writing, this version is 12 years
old. Remove backward compatibility for kernel versions <=2.6.19 from
qdf_defer.

Change-Id: I623aa5b1ed597c76997bf397d9f2114cdf8c5ece
CRs-Fixed: 2247714
2 files changed