fpga: virtex2: Fix printf format string warnings

Warning appears if built with FPGA_DEBUG defined:

  CC      drivers/fpga/virtex2.o
/mnt/data/adahl/src/u-boot/drivers/fpga/virtex2.c: In function ‘virtex2_ssm_load’:
/mnt/data/adahl/src/u-boot/drivers/fpga/virtex2.c:333:11: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘size_t’ {aka ‘long unsigned int’} [-Wformat=]
    PRINTF("%s:%d:done went active early, bytecount = %d\n",
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
           __func__, __LINE__, bytecount);
                               ~~~~~~~~~
/mnt/data/adahl/src/u-boot/drivers/fpga/virtex2.c:25:37: note: in definition of macro ‘PRINTF’
 #define PRINTF(fmt, args...) printf(fmt, ##args)
                                     ^~~
/mnt/data/adahl/src/u-boot/drivers/fpga/virtex2.c: In function ‘virtex2_ss_load’:
/mnt/data/adahl/src/u-boot/drivers/fpga/virtex2.c:468:12: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘size_t’ {aka ‘long unsigned int’} [-Wformat=]
     PRINTF("%s:%d:done went active early, bytecount = %d\n",
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            __func__, __LINE__, bytecount);
                                ~~~~~~~~~
/mnt/data/adahl/src/u-boot/drivers/fpga/virtex2.c:25:37: note: in definition of macro ‘PRINTF’
 #define PRINTF(fmt, args...) printf(fmt, ##args)
                                     ^~~

Signed-off-by: Alexander Dahl <ada@thorsis.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/20221007122003.11239-5-ada@thorsis.com