[MTD] Fix invalid default value of CONFIG_MTD_PCMCIA_ANONYMOUS in Kconfig

Default values for boolean and tristate options can only be 'y', 'm' or 'n'.
This patch removes wrong default for MTD_PCMCIA_ANONYMOUS.

Signed-off-by: Jean-Luc Leger <jean-luc.leger@dspnet.fr.eu.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>