phy: ralink: phy-mt7621-pci: drop 'COMPILE_TEST' from Kconfig

phy: ralink: phy-mt7621-pci: drop 'COMPILE_TEST' from Kconfig

This driver includes the following two files directly:
- mt7621.h
- ralink_regs.h

Compilation for its related platform properly works because
its real path is included in 'arch/mips/ralink/Platform' as
cflags.

This driver depends on RALINK but also is enabled for COMPILE_TEST
where nothing about its platform is known and this directly
included files are not found at all breaking compilation.

If we want 'COMPILE_TEST' we have to change cflags also inside
'phy/ralink' subdirectory Makefile which seems that does not
like to linux-phy maintainers. Hence remove COMPILE_TEST from
Kconfig to avoid the problem.

Fixes: d87da32372a0 ("phy: ralink: Add PHY driver for MT7621 PCIe PHY")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20201201112051.17463-2-sergio.paracuellos@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>