platform/x86: pmc_atom: dont export pmc_atom_read - no modular users

There is only one user of pmc_atom_read in tree, and that is in
drivers/acpi/acpi_lpss.c -- which can't be anything but built-in.

As such there is no point in adding this function to the global symbol
list exported to modules.

Note that there is no <linux/export.h> include removal since the code
was getting that header implicitly.

Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Aubrey Li <aubrey.li@linux.intel.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Mark Gross <markgross@kernel.org>
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Link: https://lore.kernel.org/r/20220428062430.31010-4-paul.gortmaker@windriver.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>