Altera TSE: Fix sparse errors and warnings

This patch fixes the many sparse errors and warnings contained in the
initial submission of the Altera Triple Speed Ethernet driver, and a
few minor cppcheck warnings. Changes are tested on ARM and NIOS2
example designs, and compile tested against multiple architectures.
Typical issues addressed were as follows:

altera_tse_ethtool.c:136:19: warning: incorrect type in argument
    1 (different address spaces)
altera_tse_ethtool.c:136:19:    expected void const volatile
    [noderef] <asn:2>*addr
altera_tse_ethtool.c:136:19:    got unsigned int *<noident>
...
altera_sgdma.c:129:31: warning: cast removes address space of
    expression

Signed-off-by: Vince Bridgers <vbridgers2013@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>