Tegra: Change Tegra20 to Tegra in common code, prep for T30

Convert TEGRA20_ defines to either TEGRA_ or NV_PA_ where appropriate.
Convert tegra20_ source file and function names to tegra_, also.

Upcoming Tegra30 port will use common code/defines/names where possible.

Signed-off-by: Tom Warren <twarren@nvidia.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
diff --git a/drivers/spi/tegra_spi.c b/drivers/spi/tegra_spi.c
index 2355e02..18b00b2 100644
--- a/drivers/spi/tegra_spi.c
+++ b/drivers/spi/tegra_spi.c
@@ -72,9 +72,9 @@
 		return NULL;
 	}
 
-	if (max_hz > TEGRA20_SPI_MAX_FREQ) {
+	if (max_hz > TEGRA_SPI_MAX_FREQ) {
 		printf("SPI error: unsupported frequency %d Hz. Max frequency"
-			" is %d Hz\n", max_hz, TEGRA20_SPI_MAX_FREQ);
+			" is %d Hz\n", max_hz, TEGRA_SPI_MAX_FREQ);
 		return NULL;
 	}
 
@@ -86,7 +86,7 @@
 	spi->slave.bus = bus;
 	spi->slave.cs = cs;
 	spi->freq = max_hz;
-	spi->regs = (struct spi_tegra *)TEGRA20_SPI_BASE;
+	spi->regs = (struct spi_tegra *)NV_PA_SPI_BASE;
 	spi->mode = mode;
 
 	return &spi->slave;