altera_qspi: initialize instr.mtd in flash_erase

Initialize instr.mtd in flash_erase(). This fixes the system
hang issue when CONFIG_MTD_PARTITIONS is selected.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Acked-by: Marek Vasut <marex@denx.de>
1 file changed