platform/x86: intel_ips: remove redundant variables slope and offset

Variables slope and offset are being assigned but are never used hence
they are redundant and can be removed.

Cleans up clang warnings:
warning: variable 'slope' set but not used [-Wunused-but-set-variable]
warning: variable 'offset' set but not used [-Wunused-but-set-variable]
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/intel_ips.c

@@ -858,10 +858,7 @@ static u16 read_mgtv(struct ips_driver *ips)
 
 static u16 read_ptv(struct ips_driver *ips)
 {
-	u16 val, slope, offset;
-
-	slope = (ips->pta_val & PTA_SLOPE_MASK) >> PTA_SLOPE_SHIFT;
-	offset = ips->pta_val & PTA_OFFSET_MASK;
+	u16 val;
 
 	val = thm_readw(THM_PTV) & PTV_MASK;