Some SD card init fixes.

[profi200]

• Makes sure the SD card is initialized at no more than 400 kHz +-20 kHz tolerance.
• Give the SD card the correct voltage range.
• Disable DAT3 pull-up before going into 4-bit mode.
• Prevents some clock glitches when the command and clock state machine starts.
• Makes sure CMD and DAT lines are high before starting the clock.
• Prevents skipped SD commands (makes SD init succeed first try).
• Makes SD init more spec compliant.

Additionally this:

• Sets all unused GPIOs to inputs with pull-down. Inputs later disabled to save power.
• Sets GPIO slew rate to slow. This is more than sufficient for speeds up to 25 MHz.

What's not fixed is clock glitches on command response timeouts. This is due to restarting the state machine while it's clocking the SD.

[profi200]

Caveat:
The DSpico might be detected too late on DSi systems. There is a noticeably delay between card insert and the icon appearing.

[profi200]

Should i also include this change?

diff --git a/src/main.cpp b/src/main.cpp
index ae41135..6947b79 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -208,9 +208,9 @@ static inline void earlyGpioInit(void)
     gpio_disable_pulls(SDIO_D3);
 #endif
 
-    gpio_pull_down(PIN_RST);
-    gpio_pull_up(PIN_CEB);
-    gpio_pull_up(PIN_WREB);
+    gpio_disable_pulls(PIN_RST);
+    gpio_disable_pulls(PIN_CEB);
+    gpio_disable_pulls(PIN_WREB);
     gpio_disable_pulls(PIN_D0);
     gpio_disable_pulls(PIN_D1);
     gpio_disable_pulls(PIN_D2);
@@ -219,7 +219,7 @@ static inline void earlyGpioInit(void)
     gpio_disable_pulls(PIN_D5);
     gpio_disable_pulls(PIN_D6);
     gpio_disable_pulls(PIN_D7);
-    gpio_pull_up(PIN_CS2);
+    gpio_disable_pulls(PIN_CS2);
 
     // Set SDIO and NTRCARD DAT pin slew rate.
     // Default slew rate after reset is slow. Good enough for 25 MHz.

Actually i just did because why not if i'm in there already? That change was tested.