net: caif: remove redundant re-assignment of pointer pfrm

The pointer pfrm is initialized and then later re-assigned the same
value and hence the second assignment is redundant and can be removed.

Cleans up clang warning:
drivers/net/caif/caif_hsi.c:222:6: warning: Value stored to 'pfrm'
during its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>