fpga: dfl: pci: reduce the scope of variable 'ret'

This is to fix lkp cppcheck warnings:

 drivers/fpga/dfl-pci.c:230:6: warning: The scope of the variable 'ret' can be reduced. [variableScope]
    int ret = 0;
        ^

 drivers/fpga/dfl-pci.c:230:10: warning: Variable 'ret' is assigned a value that is never used. [unreadVariable]
    int ret = 0;
            ^

Fixes: 3c2760b7 ("fpga: dfl: pci: fix return value of cci_pci_sriov_configure")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Acked-by: Wu Hao <hao.wu@intel.com>
Reviewed-by: Tom Rix <trix@redhat.com>
Signed-off-by: Moritz Fischer <mdf@kernel.org>