Prevent .noinit section from incorrect placement for AVR.

Prevent .noinit section from incorrect placement for AVR.

When .data and .bss sections are empty .noinit section is placed at data
region's start. This will be incorrect for devices that has different
data start address than data region start in linker script.
The patch updates .noinit section's VMA to end of .bss section. So, .noinit
section will be placed at .data section address (-Tdata=<address>) when .data
and .bss sections are empty.

ld/

	* scripttempl/avr.sc (.noinit): Force .noinit VMA to end of .bss VMA.
	* scripttempl/avrtiny.sc (.noinit): Likewise.