disk: efi: correct the overlap check on GPT header and PTE

disk: efi: correct the overlap check on GPT header and PTE

the partition starting at 0x4400 is refused with overlap error:
  $> gpt write mmc 0 "name=test,start=0x4400,size=0"
  Writing GPT: Partition overlap
  error!

even if the 0x4400 is the first available offset for LBA35 with default
value:
- MBR=LBA1
- GPT header=LBA2
- PTE= 32 LBAs (128 entry), 3 to 34

And the command to have one partition for all the disk failed also :
  $> gpt write mmc 0 "name=test,size=0"

After the patch :

  $> gpt write mmc 0 "name=test,size=0"
  Writing GPT: success!
  $> part list mmc 0

  Partition Map for MMC device 0  --   Partition Type: EFI

  Part	Start LBA	End LBA		Name
	Attributes
	Type GUID
	Partition GUID
  1	0x00000022	0x01ce9fde	"test"
	attrs:	0x0000000000000000
	type:	ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
	type:	data
	guid:	b4b84b8a-04e3-4000-0036-aff5c9c495b1

And 0x22 = 34 LBA => offset = 0x4400 is accepted as expected

Reviewed-by: Łukasz Majewski <lukma@denx.de>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>