Return correct peripheral clock rate for MAX32657 SPI

MAX32657 SPI input clock rate should be APB clock divided by two.

Signed-off-by: Tahsin Mutlugun <Tahsin.Mutlugun@analog.com>

Libraries/PeriphDrivers/Source/SPI/spi_me30.c

@@ -136,40 +136,9 @@ int MXC_SPI_ReadyForSleep(mxc_spi_regs_t *spi)
 
 int MXC_SPI_GetPeripheralClock(mxc_spi_regs_t *spi)
 {
-    int retval;
-
-    // TODO(ME30): Validate this logic
-    int sys_clk = (MXC_GCR->clkctrl & MXC_F_GCR_CLKCTRL_SYSCLK_SEL) >>
-                  MXC_F_GCR_CLKCTRL_SYSCLK_SEL_POS;
-    switch (sys_clk) {
-    case MXC_SYS_CLOCK_IPO:
-        retval = IPO_FREQ;
-        break;
-    case MXC_SYS_CLOCK_IBRO:
-        retval = IBRO_FREQ;
-        break;
-    case MXC_SYS_CLOCK_INRO:
-        retval = INRO_FREQ;
-        break;
-    case MXC_SYS_CLOCK_ERTCO:
-        retval = ERTCO_FREQ;
-        break;
-        // TODO(ME30): EXTCLK definition is missing from registers
-        // case MXC_SYS_CLOCK_EXTCLK:
-        //     retval = EXTCLK_FREQ;
-        //     break;
-#if TARGET_NUM == 32655 || TARGET_NUM == 32680
-    case MXC_SYS_CLOCK_ERFO:
-        retval = ERFO_FREQ;
-        break;
-#endif
-    default:
-        return E_BAD_STATE;
-    }
-
-    retval /= 2;
+    (void)spi;
 
-    return retval;
+    return PeripheralClock / 2;
 }
 
 int MXC_SPI_SetFrequency(mxc_spi_regs_t *spi, unsigned int hz)