Revert "ACPI / SBS: Add 5 us delay to fix SBS hangs on MacBook"

Revert commit 3349fb64b2 (ACPI / SBS: Add 5 us delay to fix SBS
hangs on MacBook), since the delay introduced by it is not necessary
any more after commit add68d6aa9 (ACPI / SMBus: Fix boot stalls /
high CPU caused by reentrant code).

Signed-off-by: Chris Bainbridge <chris.bainbridge@gmail.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/sbshc.c

@@ -14,7 +14,6 @@
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
-#include <linux/dmi.h>
 #include "sbshc.h"
 
 #define PREFIX "ACPI: "
@@ -89,8 +88,6 @@ enum acpi_smb_offset {
 	ACPI_SMB_ALARM_DATA = 0x26,	/* 2 bytes alarm data */
 };
 
-static bool macbook;
-
 static inline int smb_hc_read(struct acpi_smb_hc *hc, u8 address, u8 *data)
 {
 	return ec_read(hc->offset + address, data);
@@ -121,8 +118,6 @@ static int acpi_smbus_transaction(struct acpi_smb_hc *hc, u8 protocol,
 
 	mutex_lock(&hc->lock);
 	hc->done = false;
-	if (macbook)
-		udelay(5);
 	if (smb_hc_read(hc, ACPI_SMB_PROTOCOL, &temp))
 		goto end;
 	if (temp) {
@@ -250,29 +245,12 @@ extern int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
 			      acpi_handle handle, acpi_ec_query_func func,
 			      void *data);
 
-static int macbook_dmi_match(const struct dmi_system_id *d)
-{
-	pr_debug("Detected MacBook, enabling workaround\n");
-	macbook = true;
-	return 0;
-}
-
-static struct dmi_system_id acpi_smbus_dmi_table[] = {
-	{ macbook_dmi_match, "Apple MacBook", {
-	  DMI_MATCH(DMI_BOARD_VENDOR, "Apple"),
-	  DMI_MATCH(DMI_PRODUCT_NAME, "MacBook") },
-	},
-	{ },
-};
-
 static int acpi_smbus_hc_add(struct acpi_device *device)
 {
 	int status;
 	unsigned long long val;
 	struct acpi_smb_hc *hc;
 
-	dmi_check_system(acpi_smbus_dmi_table);
-
 	if (!device)
 		return -EINVAL;