bnxt_en: Fix bug in ethtool -L.

When changing channels from combined to rx/tx or vice versa, the code
uses the wrong "sh" parameter to determine if we are reserving rings
for shared or non-shared mode.  It should be using the ethtool requested
"sh" parameter instead of the current "sh" parameter.

Fix it by passing the "sh" parameter to bnxt_reserve_rings().  For
ethtool, we will pass in the requested "sh" parameter.

Fixes: 391be5c2 ("bnxt_en: Implement new scheme to reserve tx rings.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>