shields: lmp90100: drop GPIO and EEPROM priority override

Drop the GPIO and EEPROM priority override. The current settings have
been introduced as part of a major priority refactoring but I don't
think they are needed anymore, and they currently result in this error:

ERROR: /soc/spi@4002d000 POST_KERNEL 70 <
	/soc/gpio@400ff100 POST_KERNEL 99

found with:

west build -p -b frdm_k64f samples/shields/lmp90100_evb/rtd \
	     -DCONFIG_CHECK_INIT_PRIORITIES=y

Dropping the two overrides should work fine, leaving the ADC override as
that seems like is still needed.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>