or1k: increase linux TEXT_START_ADDR to 0x2000

Override the default value of 0x0000 defined in
TEXT_START_ADDR to avoid linux executables to be mapped
at zero page.

ld/
	* emulparams/elf32or1k_linux.sh (TEXT_START_ADDR): Increase from
	0x0 to first page boundary at 0x2000.

Conflicts:
	ld/ChangeLog