brcmsmac: Use kvmalloc() for ucode allocations

The ucode chunk might be relatively large and the allocation with
kmalloc() may fail occasionally.  Since the data isn't DMA-transferred
but by manual loops, we can use vmalloc instead of kmalloc.
For a better performance, though, kvmalloc() would be the best choice
in such a case, so let's replace with it.

Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1103431


Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>