Since ACPI_PTR() is used to NULLify the value when !CONFIG_ACPI,
'struct sdhci_iproc_acpi_ids' becomes defined but unused.

Fixes the following W=1 kernel build warning:

 mmc/host/sdhci-iproc.c:297:36: warning: ‘sdhci_iproc_acpi_ids’ defined but not used [-Wunused-const-variable=]

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20200707064701.GC3500@dellSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>