staging: gs_fpgpaboot: fix compiler warning with make W=1

the following compiler warning has been fixed:

drivers/staging/gs_fpgaboot/gs_fpgaboot.c: In function ‘gs_read_bitstream’:
drivers/staging/gs_fpgaboot/gs_fpgaboot.c:160:6: warning: variable ‘size’ set but not used [-Wunused-but-set-variable]
  CC      drivers/staging/gs_fpgaboot/io.o
  LD      drivers/staging/gs_fpgaboot/gs_fpga.o
  LD      drivers/staging/gs_fpgaboot/built-in.o

by removing the size variable.
Signed-off-by: Devendra Naga <devendranaga4@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gs_fpgaboot/gs_fpgaboot.c

@@ -136,12 +136,10 @@ static void gs_print_header(struct fpgaimage *fimage)
 static void gs_read_bitstream(struct fpgaimage *fimage)
 {
 	char *bitdata;
-	int size;
 	int offset;
 
 	offset = 0;
 	bitdata = (char *)fimage->fw_entry->data;
-	size = fimage->fw_entry->size;
 
 	readmagic_bitstream(bitdata, &offset);
 	readinfo_bitstream(bitdata, fimage->filename, &offset);