MAINTAINERS: usb: phy: update patterns

Commit a0e63123 ("usb: phy: move all PHY drivers to
drivers/usb/phy/") deleted the files, remove the file pattern.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>