cpuimx25sd: fix Kconfig

in 0d6cfa3a I fixed the mach-types
records. We also need to make the name consistent in Kconfig else
the machine_is_eukrea_cpuimx25sd macro fails, and thus audio codec
is not properly initalized.

Signed-off-by: Eric Bénard <eric@eukrea.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>