MdeModulePkg: HiiDatabaseDxe: HiiStringToImage() should not overwrite BltX
MdeModulePkg: HiiDatabaseDxe: HiiStringToImage() should not overwrite BltX

when has next line to draw, should not overwrite the BltX
to 0, instead should keep the BltX value that pass into
StringToImage function.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <1e8692d8ed8470b17e8ddd7612a0f029768dcb56@intel.com>
Reviewed-by: Eric Dong <fa9eeec52367040ac98013bc4b2913db170588f8@intel.com>
Reviewed-by: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>
Acked-by: Laszlo Ersek <7437296077edea1cb64451c122c4dac071f0cfbc@redhat.com>

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