[igbvf] Remove conflicting macro definitions

Remove macros which aren't used anywhere in the driver, and which
conflict with macros of the same name used in the EFI headers.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/igbvf/igbvf_osdep.h

     true = 1
 } boolean_t;
 
-#define TRUE  1
-#define FALSE 0
-
 #define usec_delay(x) udelay(x)
 #define msec_delay(x) mdelay(x)
 #define msec_delay_irq(x) mdelay(x)