[Makefile] Remove obsolete SRCDIRS

src/Makefile

 SRCDIRS		+= drivers/net
 SRCDIRS		+= drivers/net/e1000
 SRCDIRS		+= drivers/block
-SRCDIRS		+= drivers/scsi
-SRCDIRS		+= drivers/ata
 SRCDIRS		+= drivers/nvs
 SRCDIRS		+= drivers/bitbash
 SRCDIRS		+= drivers/infiniband

src/arch/i386/Makefile

 SRCDIRS		+= arch/i386/firmware/pcbios
 SRCDIRS		+= arch/i386/image
 SRCDIRS		+= arch/i386/drivers
-SRCDIRS		+= arch/i386/drivers/bus
 SRCDIRS		+= arch/i386/drivers/net
-SRCDIRS		+= arch/i386/drivers/disk
 SRCDIRS		+= arch/i386/interface/pcbios
 SRCDIRS		+= arch/i386/interface/pxe