target: apq8084: correct the command line buffer size check
target: apq8084: correct the command line buffer size check

Provide proper string length for HDMI command line check to
avoid wrong buffer length check

Change-Id: I34ad9f01debfa28687d7ede7aa47a73192a69569

Foxda-Tech/polaris-bootable-bootloader-lk,Foxda-Tech/polaris-bootable-bootloader-lk,Foxda-Tech/polaris-bootable-bootloader-lk,efidroid/lk,efidroid/lk,CanarySolutions/little-kernel,CanarySolutions/little-kernel,CanarySolutions/little-kernel,efidroid/lk,Foxda-Tech/polaris-bootable-bootloader-lk,Foxda-Tech/polaris-bootable-bootloader-lk,efidroid/lk,efidroid/lk,CanarySolutions/little-kernel,CanarySolutions/little-kernel