mach-pcm037_eet: fix compile errors

this patch fix the following errors :
arch/arm/mach-mx3/mach-pcm037_eet.c:62: error: implicit declaration of function 'MXC_SPI_CS'
arch/arm/mach-mx3/mach-pcm037_eet.c:185: error: implicit declaration of function 'imx35_add_spi_imx0'

from the Kconfig pcm037 is i.MX31 based and not i.MX35 so replace
imx35_add_spi_imx0 by imx31_add_spi_imx0

Signed-off-by: Eric Bénard <eric@eukrea.com>
[ukl: remove unneeded #include <mach/spi.h>]
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>