arch/arm/rp23xx: add dsp/fpu extensions support

Each Arm Cortex-M33 processor in RP2350 is configured with Single
precision FPU and DSP extension

arch/arm/Kconfig

@@ -387,6 +387,8 @@ config ARCH_CHIP_RP23XX
 	select ARCH_HAVE_MULTICPU
 	select ARCH_HAVE_I2CRESET
 	select ARM_HAVE_WFE_SEV
+	select ARM_HAVE_DSP
+	select ARCH_HAVE_FPU
 	select ARCH_HAVE_CUSTOM_TESTSET
 	select ARCH_HAVE_PWM_MULTICHAN
 	select ARCH_BOARD_COMMON

arch/arm/src/rp23xx/rp23xx_start.c

@@ -156,6 +156,10 @@ void __start(void)
       putreg32(0, RP23XX_SIO_SPINLOCK(safe_spinlocks[i]));
     }
 
+  /* Initialize the FPU */
+
+  arm_fpuconfig();
+
   /* Configure the uart so that we can get debug output as soon as possible */
 
   rp23xx_lowsetup();