ramips: fix support for MX25L25635F flash

ramips: fix support for MX25L25635F flash

Patch picked from commit 82618062cf7e

This enables 4B opcodes for MX25L25635F, to fix the reboot crash
issue (FS#1120) At least 3 devices are using this flash
- GeHua GHL-R-001
- Youku YK1
- Newifi D1

Now the MX25L25635F can be correctly detected without breaking MX25L25635E
[ 3.034324] spi-mt7621 1e000b00.spi: sys_freq: 220000000
[ 3.045962] m25p80 spi0.0: mx25l25635f (32768 Kbytes)
[ 3.056098] 4 fixed-partitions partitions found on MTD device spi0.0
[ 3.068748] Creating 4 MTD partitions on "spi0.0":

Signed-off-by: Deng Qingfang <dengqf6@mail2.sysu.edu.cn>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com> [added deprecation notice]