nfc: mrvl: reduce the scope of local variables

In two places the 'ep_desc' and 'skb' local variables are used only
within if() or for() block, so they scope can be reduced which makes the
entire code slightly easier to follow.  No functional change.

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>